Stereo live streaming on Facebook with a Presonus Studiolive 16.0.2 USB

Attention, here is an article for the audio geeks! Problem I do live broadcast on Facebook every week and I wanted to broadcast in stereo. Problem: the console Presonus Studiolive 16.0.2 USB is seen on my MacBook only with as the first two inputs of the console, I am unable to get the stereo mix