I found I needed to block a lot of things that are not school related to stop my son watching YouTube or playing games the whole time.
Originally I had to specifically allow the school education platform, Edmodo so he could do his homework while he was physically attending school.
Zoom is blocked under Remote Access Tools?
How do i ublock it???
You might need to add zoom.com as a specific website allowed during school time (and whatever other time you want).
In the Age Profile settings for the age profile relevant to your child/ren, go to "Websites" and add zoom.com as a specific website. You will be able to specify which type of time allows access to the Zoom website there.
I haven't tried this specifically for Zoom, but I have a list of other websites I have allowed in particular times for my son. For example, I had to add edmodo.com because the school uses that as its work portal.