Hey @omar.saleh, thanks for reaching out and using Zoom!
I was able to reproduce your issue. Basically the browser is blocking turning on the audio programmatically via the prefer=1 query param.
The AudioContext was not allowed to start. It must be resumed (or created) after a user gesture on the page. Chrome 自動播放政策 | Blog | Chrome for Developers
To fix this, use prefer=0 and have the user click the Join with Computer Audio button, and allow site to access microphone.
Then you should be able to hear the participant from the iFrame.
<iframe style="border:none; height: 600px; width: 100%;" src="https://zoom.us/wc/{meeting-id}/join?prefer=0&un=TWluZGF1Z2Fz" sandbox="allow-forms allow-scripts allow-same-origin" allow="microphone; camera"></iframe>
Let me know if this works!
Thanks,
Tommy