It says to select the pairing feature on the mobile app. Where is the pairing feature?
it is likely that the app you are speaking of is the Xfinity TV remote app. you have to select the TV which you want to use with the apps virtual remote. after logging in select the guide icon if not on the guide and the microphone icon. touching the little TV symbol lets you change the TV you are going to control via Comcast server (not IR). there are 3 icons across the top then to use various functions of doing remote control.