Everything should work happily over USB, but you'll probably need to set your Audio Midi output on the Mac no higher than 96khz for the 808v6 to decode it.

In my experience the sound quality will be OK but nothing magical. USB can be pretty jittery and the PC environment is electrically noisy, so I've always achieved much better results using the Mac as a controller and streaming to a dedicated end-point (MS600, 218, ID4x etc) via wifi/Ethernet, typically using Roon or similar. Doing this with Apple Music will probably require an AirPlay 2 compatible streamer, of which there aren't any (as far as I know) in the Meridian universe. However, some third-party streamers with digital outputs may be able to fill the gap.

Office: MacMini + Roon -> MS600 -> AR LS-9 -> M60s (1993 vintage)
Home: [AppleTV -> HD621] + [Roon -> 218] -> G65 -> DSP5200HC + DSP5200s + DSP3200s
Being a JAFA in Auckland, New Zealand