Both pop for me, (steam first then windows notification) might have to have xbox app and console companion installed though, not sure if that's the reason.
Are you also using this
9. Halo: The Master Chief Collection Trainer (Achievements Enabler)
along with the trainer? Run and activate at main menu then run the trainer and activate it after selecting what game you are playing. Played 3 mins of Halo 4 found a terminal and achiv popped for both.
You do know you can do that yourself, right? Just get it from the site and not the TM, right-click it and rename before moving it to the trainer manager folder.
[Edited by CyPHeR369, 12/4/2020 5:42:26 AM]