Permissions are tied to user roles. When adding users and groups to an extranet space, a role needs to be selected.
What are user roles?
When you assign a user or group to an extranet space, you must specify user roles. The permissions set by the administrator are linked to this role. You can create up to five user roles with different sets of permissions.
The boxes/checks represent the permissions. If boxes are checked, the user receives those permissions (as long as they received the role).
Define user roles
Navigate to Confluence administration → Space Privacy → Roles & Permissions → User Roles.
Click on the Edit button at the bottom of the page.
Enter the name of a role and activate the Enabled checkbox if you wish to activate the role.
Activate the checkboxes according to the permissions you want to give said user role.
Finally, click on the Save button.
When you change the permissions of a role, the permissions of all users already assigned to that role will be updated accordingly.