My wife had a good time in her singing class on Zoom. It was easy to set up and worked quite well on my Chromebook, but there still was a notable latency delay.
Worked just fine, as long as only one person sang at at time.

The free Basic Zoom membership has a 40-minute limit on meetings with 3 or more participants. Apparently, there's no time limit for one-on-one meetings.

-Joe-