That is the correct one, the harnesses are for the tpms/camera not the rear bumper harness. If you have 8-9 wires in the bottom connector you are good. Dont think there is a separate one.
Since this post has been so helpful, thought I'd update as i just installed the Ford Accessories F-150 system and it works great. I have an2022 XLT with 360 and tow package along with Pro Backup assist. Ford said I just needed to follow the instructions included with the ML3Z1A189F Camera and...