Ditto with NoiseRiser on this one.
Sorry to tell you but in short… ditch the Mac and use a Windows laptop for DJing alongside the dnx1700.
If you want to use the Mac and M1 chip for DJing then you can’t use the dnx1700 sound card. Support has ceased.
I don’t know of any 3rd party programs that you can use to hack old hardware to work on new Macs. Maybe some out there, but I’m no Mac user to do a search.
But of a conundrum to think on.
It’s noted on here in old threads if you find them from Denon officials.