The module does nothing unless you enumerate the important groups.
You do so by visiting the dialog in users/policies/identify important groups.
In this dialog, you simply name the groups which will often be assigned
to user accounts. Once you have done this, the user account dialog
(only for normal user accounts) will be modified. The field
supplementary groups is gone. A new section in the dialog
called extra groups is shown. In this section, for each
important group, there is a check-box. There is also an extra line
to enter other supplementary groups if needed.