outputting to live stream from xdj-rx HELP !!

Hi - I'm trying to connect my XDJ-RX to OBS to do live streaming .

DO I need to buy an Audio interface to connect xdj-rx

to my Mac Pro Desktop ( on Mojave )     ? which OBS will pick up 

OR  -
someone said I might be able to use the USB from the XDj 
to my MAC , and this will be picked up in OBS 
I cannot get this to work 

I've also tried booth out rca's to a single small jack - but the audio sockets on mac seem to be for output only ( OBS doesnt recognize )

Please note I'm using the XDJ-RX to mix so cannot use midi mode

If I need to buy an interface thats fine - but dont wanna waste cash If I dont need to 

thanks guys !!