For Apple or Android tablets and phones, make sure you have the most recent version of the free Zoom Cloud Meetings app installed, and ensure that the “Original Sound” feature is (1) enabled in the app and (2) activated for our meetings. See:
https://support.zoom.us/hc/en-us/articles/115003279466-Enabling-option-to-preserve-original-sound
and read the two sets of instructions that have the subheading “Mobile app”.