In the case you are trying to make your game work with any amazon device that use the Amazon Fire TV remote, I'm pretty sure the GamePad plugin its not working for You.
This is because the Amazon Fire TV remote its not been recognized as a GamePad but as a keyboard. Saying that,
Go on and add the keyboard plugin if not already in your project, after that just use the "On key code # released/pressed" condition with the Key Code for the specific controller button you need.
Amazon Fire TV Remote Key Codes Reference:
Hope this little and quick tutorial works for you and you can find it useful!