There is no option to start voice chat on the macOS client when you are a regular admin (not the owner) in basic groups or in supergroups.
As a regular admin in a basic group or a supergroup:
MacBookPro14,1, macOS 11.1
Log in here to report bugs or suggest features. Please enter your phone number in the international format and we will send a confirmation message to your account via Telegram.
We've just sent you a message.Please confirm access via Telegram