how to connect WEBRTC in unity ?

I am trying to access webrtc connection in unity. I also used webrtc video chat asset in unity( LINK :
WebRTC Video Chat | Network | Unity Asset Store) . in this plugin i cant understanding how to create sdp offer and answer.

you can follow this tutorial

i also used this example but i can’t understand how this create offer and answer. And this example is only work on webgl,android and window pc not support macos and iphone and other platforms.