I have a Quantum 4848 which I have got a week ago since the M1 driver was confirmed. First of all, you can't just install the driver, as @josephhaley1 pointed out, you need to enable the kernel extensions in Recovery Mode. At least the MacOS warns you about that.
The worst part is that my device works, for about a couple of minutes. Then disconnects for no reason and cannot reconnect by itself. Its fine with Intel base MBP + Catalina, so it seems to be an M1/Big Sur problem.
We are having back and forth with support. They are very responsive, but it seems like they are still in the dark with this. This is an expensive device, but already sounds soooo great, I want to keep it. I really hope some driver update can make it work.
Update: the issue was caused by the Thunderbolt cable. Probably the catalina driver was able to handle the dropouts, but the BigSur simply lost connection. Replacing the cable solved the problem, Quantum 4848 works flawlessly on Macbook Air M1 with BigSur.