fl studio to obs

Hi, I want to upload content of making beats to YouTube in FL Studio but my problem is that i have the focusrite Scarlett solo. when ever im In fl studio and i try to record something there is no audio.. any idea how to fix it? been trying to fix that for a long time and watch tutorials but...

OBS is recording all the sound off my desktop except for the one coming out of fl studio 20 (mac). I know that for windows you are supposed to chose ASIO or smth like that but mac doesnt have that option. I want to record production videos and I need to be able to record audio from fl to do so...