Please bear in mind the process is very finicky.
You have to "forget" any nearby wifi connection, or your device will switch back to that connection during the setup process. (I've had that problem)
You have to exactly follow the instructions. For example if the driver's door is open, the process won't work.
The button clicks have to be done really fast.
So it works like this, get in, close the door, get the app ready to link up.
Press start (DO NOT PRESS THE BRAKE PEDAL) to go into accessory mode and IMMEDIATELY click the remote buttons, alternatively.
Remember, you only have 10 seconds from the moment you press the START button.