We don’t have an Apple TV to test with, but tried something similar: setting up an AirPlay receiver on macOS 12. In that case, Vuo also did not send audio, and we spotted a log message related to sample rates. Because of this, we’re guessing that the problem is that Vuo doesn’t currently handle sample rates other than 48 kHz. Once that problem is addressed, see: Vuo does not receive live audio from Logitech USB Headset H340, we can see if that also fixes audio streaming to Apple TV.