I think you can send the stream id through singnaling channel.

https://github.com/ant-media/Ant-Media-Server/wiki/WebRTC-WebSocket-Messaging-Reference

For creating the stream in ant media server itself. You will need to call their REST api if you are doing it programatically. If not programatically you can simply create the stream from ant media ui.

https://antmedia.io/rest/#/BroadcastRestService/createBroadcast

But calling ant media api from client side might present a security risk.