Can I use the USB tether to program a Vex EDR bot if not than what do I need?
You can use this to program the robot. What programming software are you attempting to use. If you don’t have one I suggest downloading ROBOTC for free, just make a vexrobotics account and go to my account - >software
It is possible to use only the USB tether to program your robot, but I would recommend you get the VEX Programming Hardware Kit