Yes, they must send to all owners the agenda, financial report, budget, etc. and reasonable details about the subjects to be discussed at the AGM, but only required to be delivered no later than seven days before the meeting.
So I think this notice in the elevator is simply a pre-invite about the AGM which seems like a good service.
We do the same in my building, as soon as we have agreed on the date, we inform the co-owners, but let them know that the formal invitation will follow later (as we may not have financial report audited yet, received all proposals for the agenda, etc.).