@mem-com
The firsts XBox-One gamepads are not bluetooth, only the next gen :
https://www.reddit.com/r/xboxone/comments/5fr7r1/easy_way_to_tell_if_a_controller_supports/
This next gen is easy to configure in Retropie. Maybe you need to install xboxdrv in Retropie-Setup, Manage packages, Manage drivers packages.
The first Xbox-One no-bluetooth can't work.
360 pad with wireless adapter should work :