Can't add a user to the Group

I created a user on our Seafile system, but I cannot find anywhere that allows me to add them to a group. Please explain how I do this?

First you have to add the user to the system and create a new group or use a existing one.

Now you have to open the group in the webinterface:

Here you have to click on the settings button and then use the option manage members. After this, you can add new users: