Official comment
Ola Gerardo,
The correct drivers for macOS Big Sur are located here.
Please note that there is a bug with macOS 11.4 which may cause the drivers not to load after reboot. Instead of reinstalling the drivers, you can force-load the drivers through the terminal with this command:sudo kmutil load -p /Library/Extensions/DJM-850\ USBAudio.kext/
Enter that and your password and it should allow you to use the DJM.