Correct, unlike with Delta where, as I once learned the hard way, you have to get the bag to an agent by their cutoff time. "But you saw me in line as you haggled with the guy in front of me for 5 minutes over his bag weight, and now it's only 1 minute past the deadline" was not an acceptable excuse.

Still, best to be checked in with the app already on AA, because if you start with the kiosk at 45:01 and then can't check in (for whatever reason), you're SOL.