
Did you have the XDJ-RX connected when that appeared? If I switch my audio input after rekordbox is open and I don't have the RX connected to the computer, I get that message, but then connecting it shows the device configured for outputs.
Tested with Windows 10 (64bit) and rekordbox 4.1.1, XDJ-RX driver v1.0
Can you scroll to the bottom of that Audio page and tell me if the RX shows up in the Control Device Information section?