Know that you're not the only one experiencing issues! No matter what I do, I cannot for the life of me get the Oculus Quest's built in microphone OR speakers to work with Oculus Link. I've had to resort to wearing my pair of Logitech headphones (which thank goodness have a very long cable) for sound & microphone purposes on top of my Oculus Quest.
I've tried troubleshooting it, and researching to see if anyone else has had this issue, and all I get is "stale answers", which are beating around the bush not answering our issue.
Hopefully, the Oculus Development Team can push out a patch, or at the very least a guide on how to fix it ourselves in the meantime so we don't have to resort to unconventional means to get something as simple as sound to work. (Or if someone else has a fix for it, please post it below!)