I can't guarantee that someone would be there at 21:00 hrs, but in theory there should be if there was a late EI flight and especially if there were connecting passengers (same booking). But if there isn't anyone there you would be allowed airside with say a printed itinerary - they will bring the biometrics on a sticky label instead - and then at the gate you could resolve the boarding pass. But doing it online / via the app would make sense.