You might need the app to program a switch for arming. You can use the receiver tab to see which channel is on which switch, flick them in turn and see which Aux outputs go on. Then use that to set the arm switch to the right Aux and range,
If you have it bound, then plugged in to a battery not the USB then it should arm, the motors might idle when it’s on. Joshua Bardwell has a load of videos on getting a quad to arm, he goes over all the common problems.