Rekordbox not playing to external mixer

I'm having real trouble getting rekordbox to play to an external mixer on both channels independently.

I've followed some of the previous threads and it appears that I'm missing a driver but i'm far from sure about that

The error message below occurs when i try to change the driver and it appears that it isnt listed in the sound, games and video controllers in the Device Manager but again I'm not 100% about that.

Software is not my specialty so any advice will need to be slow and basic I'm afraid

Thanks in advance