I am not aware of how to set that up, I figured the airplay was the issue but I didnt see any settings to change it. Airplay is the connection thats used no mater were I initilize the stream… from my Living room PC or the mobile app.
You should use RAAT in this case as it is Roon’s native protocol. There is no need to use Airplay.
To do that you first need to enable the device in Roon itself: go to settings->Audio and there you will find your RoPieee unit with the DAC. Enable it, give it a name and use that zone for playing audio.