I don’t know if I can resolve this, but I’ve done some reading and the m2/m4 have some known issues with Linux.
Some patches and configs and instructions are here:
https://github.com/kiosion/alsa-motu-m2
Aside from that, there could be another application that is locking the card which is why you’re getting the resource busy error.
As mentioned here:
And some more issues/troubleshooting specifically with the m4:
https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/3312
Wouldn’t and couldn’t.