I understand that IOS devices currently use AAC over Airplay 2, not ALAC, even if the source was originally ALAC (or other lossless format). I’m sure you will do the due diligence, but be careful that ZS doesn’t disenfranchise those of us who are happy with Airplay 1 sending 16/44.1 to ZS from Apple Music source on iPhone or iPad.
It will support both Airplay 1 and 2.