Trading on controller

Does anyone know how to trade on controller? When I get a trade request, it says to press start but this merely opens the pause menu. I also tried holding it but see no options their either. I have been waiting for it to time out then send a request of my own to trade while using controller on PC which i actually great btw.

Edit: Figured it out for those having trouble. It is in fact under the start button but mine was cut off to the left, you have to hit start then navigate to the right side to hit Accept there manually.