Zoom app won't cast audio via Miracast
This article https://support.google.com/chromecast/thread/41716778?hl=en may answer your question indirectly.
I have similar problem on TV Box. Skype works but Zoom has no audio. I have posted question in this forum.
I guess that one solution is to route the &quot;call over internet&quot; to HDMI. I am doing research on how to do it now.