No one will be there for you. Our flight was delayed on Sunday, and we didn’t arrive at Cabana Bay until 6:30. The ticket desk closed at 6:00, and we were told we had to go to Citywalk or guest services at one of the parks if we wanted our APs that night. We ended up waiting nearly 40 minutes at guest services to pick them up, and only made it into US half an hour before close, but it was better than doing it the next morning.
If you are planning to rope drop, my advice is to get to the parks really early (or as early as you can manage given your late arrival time), and send one person to guest services (whoever paid for the AP and tickets) while everyone else holds your place in the entrance line. Otherwise, plan for a chill first day, and mentally adjust your expectations to account for a wait.
However, we had no problem checking in with the AP rate without an AP in hand, so don’t worry about that aspect. But if your only reason for an AP is the hotel rate, be sure to check other options. Sometimes the Savvy Traveler rate is better or you can get a lower rate through a third party seller. The AP rates can be great, but they’re not always available, and they’re not always the cheapest.