Be aware that I adapted the inner diameter of the "hole" for the motion sensor to have it come out the proper size on my printer.

I recommend printing a few layers and then check if your sensor fits into the opening at the base of the holder. If not, simply adjust the size of the holder in your slicer and try again. But don´t be to generous with enlarging, it has to be a tight fit or the sensor will fall out.

For horizontal installation at the ceiling the sensor stays in place by gravity alone but if you use it vertically it might be a good idea to simply stuff some tissue paper behind it (doesn´t hurt for horizontal installation either) to keep it in place.