User Roles and permissions are managed from Home, inside of “Team Members”. (shown below). There are two roles users can have:
Administrators have access to both Design Studio, Content Studio, and Team Members, your new team management. They create the Template and Blocks system for Content Studio users.
The "Invite new team members" permission is initially only available to the Account Owner, but they can grant that permission to other users, and once those users have the permission they can grant it to other users.
Content Studio Users, use Content Studio to edit and publish from Templates and Blocks.
Full Permissions List Below