Which pin on Teensy 4.0 can I use as an interrupt pin. Do I need to uploud any code to calirfy that it is an interrupt pin or can I just plug in my cable there without any problems.
Quick read of specs looks like all pins on teensy 4.0 are interrupt capable.
(This is not unusual on newer/more capable/more expensive microcontrollers)
You will need a suitable interrupt handler.