Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
I also have this same problem but it is not too big for the screen. It is a small box with a close button but nothing to accept and close. It keeps coming back
Update, i found that Office was signed in on an old account so i closed that and signed in on the correct account and the pop ups stopped. However, I came in this morning and somehow it had reverted to the other account and the same problem occurred. Signing out fixed it again, but it is going to be a pain to have to do that everyday!