Cross DJ free and external mixer

Hi all,
Would anyone be able to tell me if I can use the free version for Mac with an external mixer? I have tried to set it up but with no luck. I have a MacBook Pro connected with FireWire to my focusrite saffire pro24 audio interface and connected outputs 3,4,5,6 to channel 2 and 3 of my Numark DM 2000X mixer but it all seems to be coming out together and I'm not sure what to set up in the saffire mix control user interface.....
A big ask I know for help but I have a party to do tomorrow and I'm stuck..
Regards
Phil
Would anyone be able to tell me if I can use the free version for Mac with an external mixer? I have tried to set it up but with no luck. I have a MacBook Pro connected with FireWire to my focusrite saffire pro24 audio interface and connected outputs 3,4,5,6 to channel 2 and 3 of my Numark DM 2000X mixer but it all seems to be coming out together and I'm not sure what to set up in the saffire mix control user interface.....
A big ask I know for help but I have a party to do tomorrow and I'm stuck..
Regards
Phil