My first thought is, are you plugged into the PM3 correctly, (top short edge) if not, you aren’t the first and won’t be the last…
Next, it my be the button press and hold dealio you need to do…I’m not sure if it is the same on PC and Mac sorry. but should be in the same guide as I linked below 
Otherwise are you following this guide?
There may also be some pointers in this recent thread if you get stuck along the way