There are limits to what these devices can do, and that limits how they can be connected. To start, we need to understand exactly how you want the lights to respond.
Do you want this?
Temporarily forget the motion detector. The lights should operate exactly like a common 3-way circuit, so that flipping EITHER switch can turn the lights on or off. Now add the motion detector so that, whatever the lights are doing, the detector can turn those lights ON, and later can remove that power so the lights turn off IF the manual switches have NOT been changed. However, the motion detector has no way to force the lights off if the manual switches are already feeding power to the lights. To do this we CAN arrange a circuit that has the motion detector act like a bypass that forces the lights on no matter what they are doing, but cannot force them off of they are on already from another power source.
If that's what you want, I have designed (and am about to install) something similar for exterior lights on my new garage. I have one fixture with a built-in motion detector, and I will connect to its light socket two other fixtures at different positions so they all work together. Then I have a Smart Switch to act as a bypass to force all lights on no matter what the motion detector says. If I turn OFF the smart switch, the lights might still be lit up if the motion detector is feeding power to them but that will stop when motion stops. This is similar to your case - the motion detector is the bypass switch that can force lights on, but can turn them off only if the Smart Switch is already in the OFF position. The difference is that, in my case I am using only one switch instead of two in a 3-way connection.
Here come the limits. My first concern was whether or not the motion detector's circuit would be damaged by having its OUTPUT connected to full power from a separate source when the detector is NOT trying to feed power out. Of course, the source of that power MUST be the SAME as the detector's INPUT power source so those voltages are the same at all times. I contacted the makers of the fixture with the motion detector and asked about three different ways to make connections. In my case they said their unit CAN be wired with a simple bypass connection and it will not harm the detector output circuitry.
The second is in the way that Smart Switches are wired, whether single-pole or 3-way. In a typical 3-way light circuit there are two manual double-pole switches. At one end the power supply is connected to the switch Common terminal, and the switch position sends that power out on either of two output terminals. The wires leading out from that switch are both called the Traveller Lines and (along with the white Neutral line) go out to the second switch. At that switch the two Travellers are connect to the two Traveller terminals and the switch position selects which of those two to pass to the COMMON terminal of the switch. The light LOAD is connected to that Common terminal and to the white Neutral line.
MOST 3-way Smart Switches I've seen use the Hot power input line as power to their own circuits PLUS power to feed out to the load. That is, power for the switch's internal circuits is drawn from the COMMON terminal. So that works just fine for the FIRST switch in the 3-way circuit. But at the SECOND circuit location the COMMON terminal side that is used as the power supply for the switch's internal circuits gets NO power directly, because power is coming in from the first switch on only ONE of the two Traveller lines. This switch cannot do ANYTHING unless it happens to be set already to the correct Traveller. So in almost all such cases, the sellers of such Smart 3-way Switches tell you it can be used ONLY at the FIRST switch position (where the power IS supplied to the switch COMMON terminal). You MUST use a normal MANUAL 3-way switch in the SECOND position so the YOU can change its setting. I have seen a few such Smart 3-way Switches that claim you CAN use TWO of them for BOTH positions, but I do not know whether those really work or not.
So, for your purpose, OP, I suggest you buy a 3-way Smart Switch for the FIRST position in the circuit where power from your breaker panel is brought in and the Hot line connected to the COMMON terminal. Then two Traveller lines (Black and Red) plus the white Neutral line are carried in a 14/3 cable to the second switch location. At that location you install a MANUAL 3-way switch, with the two Traveller lines connected to the two separate terminals, and the output of the switch (the Common terminal) connected to the Black Hot wire of the cable feeding power to the lights. This gets you manual control of the lights from both switch locations (assuming the Smart Switch has a manual button) plus Smart Switch remote control of ONE of those switches. However, if you are NOT actually there to observe the lights' condition, remote use of that Smart Switch can NOT tell you whether or not the lights are on. A simple Smart Switch may be able to tell you through its app on your phone whether it is "on" or "off". but that really would mean only whether the switch is "up" or "down", and the position of the SECOND manual switch would determine whether the light is really on or off. Now, I can imagine that a Smart Switch design might include in its circuit a way to determine more than the switch "position" - if it actually measures the CURRENT flowing though it, it COULD tell you whether the lights are truly on or off. I don't know that detail of the switch design, but you should ASK the makers how that can work.
Anyway, so far we have a 3-way light circuit with Smart Switch control. NOW we add the Motion Detector feature. The motion detector module needs to be mounted where you need it and fed power from the SAME wires that feed the Smart Switch in the FIRST position. That MIGHT be at the first position switch box. The motion detector has two Input wires (black and white) to connect to the power feed lines, and than a Red Output line that sends power out to the load when the detector turns that "on". You MIGHT need to use a length of 14/3 cable between the motion detector and the FIRST switch box just to feed power out to the motion detector and return the "switched power" on the Red line. Now you DO need a SECOND cable from this box up to the second switch position box - this one is just 14/2, Black and White. The BLACK of this is connected to the RED coming from the motion detector to provide SWITCHED power to send up to the second switch box. At that box you splice this cable's BLACK wire (Hot from the motion detector) to the BLACK wire coming from the switch's COMMON terminal and the BLACK wire going out to the LIGHTS (load). When you connect this way, the basic 3-way switch circuit continues to act as normal (above). But when the Motion Detector turns "On", it willfeed power to the lights no matter what the 3-way switches are trying to do, and the lights go on. When motion ceases the detector turns its output "Off" and there is no more power to those lights bypassing the 3-way circuit.