According to this page,
https://marantz.custhelp.com/app/answers/detail/a_id/6713/~/marantz-avrs-supporting-airplay-2
my AV8802A does not support Airplay 2.
According to the Marantz manual,
http://manuals.marantz.com/AV8802A/EU/EN/GFNFSYjfglxuxr.php
AirPlay should be automatically selected when a device (e.g., laptop) streams to it, and “Online Music” will be selected. This does happen, but no sound is played, and the progress bar for a given track does not move.
It seems like a few others had a similar issue, but I don’t know if the RC is the same: