So I've found the problem.
on an online server of "mongodb-server" was installed.
when I changed it into "mongodb-org-server" He has shown the groups.
So it could be because it is located on the MongoDB.
Is there an option to open a chat window for a given group? I created a new group, added a few users to it, now I would like to start a chat with this group - Is this possible? I can only see an option of manually adding different members.
This is not possible yet, would be a nice enchancement. https://github.com/NodeBB/NodeBB/issues/5777