No group sound on TEAMS during classroom.

I can't hear anything the lecture says on TEAMS during a class. I can see the slides but can't hear the teacher. I can listen normally on TEAMS for iPad and on web browser in an old w7 laptop, but not on my superpower Mac mini with Teams installed on it. When taking a look at configurations, I can choose the sound output, but all of them shows a bar crossing the speaker image telling it is muted. I can't click and activate it, it won't allow me. If I choose sound output on screen speakers or on externa usb sound card I get the same problem. it is frustrating like microsoft shitsoft mtfsoft is bugsy...