Hello,
ist it possible to restrict the usage of the Contacts Addon to specific Usergroups? For Upload Restriction i can set the maximum Upload Storage for a Group to 0 but i found no way so far to make CardDav and the other functions coming with the addon available to specific users only. It would be nice to set some kind of group or permission that hides the contacts tab completely and forbids using the app for those users.
If I remember correctly you can enable apps for a set of specific groups only 
This is on the app list settings, top right menu.