FWIW, I checked in online and specified a 4pm arrival. The app kept saying "preparing room" and not providing a digital key. At some point it switched the room number. When my wife arrived at around 9-10pm, she was able to check in, at which point a digital key appeared for me in the app. She didn't have any trouble otherwise.

I do wonder why I didn't get a digital key earlier, why they switched the rooms and what to do if this happens again. Call the hotel?