How do I add "Assignments" tab to a Team

Hi,

Some user created a team an forgot to select the "Class" template:

This way they can not access the "Assignments" tab.

I tried some solutions, like the one mentioned in this video: https://www.youtube.com/watch?v=9v7LsmZ8FLg&lc=UgxS4WQunr0zOs355D14AaABAg.9JAx1rm8sPF9JwrerIk5xU&feature=em-comments 

The problem is that i can not find the assigments app in my tennant.

Is there something at the admin level i showld check?

Thanks