In the Groups tab of the wp2print >> Settings administrative page, you can configure how users are added to their groups
The "Rapid user search to add select users in groups" option allows to you to turn on/off a rapid search bar for customers to add as users when creating a new group. If you choose to enable this feature, you will use a similar search bar to the one below when adding new users to a group:
The setting allows Group approvers to add/delete users of a group. You can set the Group approvers of a group when you create the group, in the menu shown below: