Perform the GUM check before your prompt the user with a join button to click. Apple requires permissions to be allowed first before interaction occurs.
If elements are not auto-playing it’s due to some HTML/JS adjustments required.
HTML:
<video video-id="1234567" autoplay playsinline>Your browser does not support the video tag...</video>
Above would solve the HTML issue if element doesn’t contain autoplay/playsinline attribute. Beyond that for JS you’d resume() the consumed track and add this track to a MediaStream attach it to an element and play() it.
Good luck.