flx lights up but does not nothing else. I'm a newbie. what am i doing wrong!

i have just tried to connect flx4 to pc for 1st time. it lights up but does nothing else. it is plugged into mains and type c / usb is liknked with my macbook air. rokordbox is on, set in performance but plays through pc speakers. i have rca's from controller to amplifier /speakers set up. can anyone help as every youtube tutorial assumes i am past this stage.