I thought that to add a user who requested a membership to a group, we group admins would only need to go into the respective group page, such as the activism one, but found myself confused not to see those who applied for membership listed there.
In any case, you can click on add members there, but I wonder if there isn’t an overview of people who requested a membership. Maybe you know it @yala?
Use the Add Members (one by one) or the Bulk Add Members (multiple at once) button
Insert the username(s) to be added
At this point the user is part of the group and should be able to access any forum categories restricted to it. It may be useful to reply to the original request of the user to join the group, so that she is informed about the subscription.
I am unable to reproduce this, since I have never received such a group joining request. Should we stage such a scenario in a testing environment and triage the associated user flows?