You need these programs which I will link here Sound Flower : https://github.com/mattingalls/Soundflower/releases and Sound Siphon 2.1.1 : https://staticz.zendesk.com/hc/en-us/articles/360000041912-Sound-Siphon-2-1-1-Release-Notes-and-Download (HAS TO BE 2.1.1 3.0 DOESN'T WORK) Here is the video tutorial : Watch in 720p I don't know why you need soundflower, but it just works somehow

The only programs I know that work with this are : OBS Studio (any version) and Iris : Screen Recorder (what i use, versions before sound siphon 3.0)