As a Project Administrator you can add as many user roles as needed. You can only assign either edit or view permissions to each role.

How to add new user roles

1. Click the gear icon in the bottom of the sidebar to go to Project Settings.  
2. Click the sub-section Users. 
3. In the Roles card you see a system generated user role with Edit permission called Default.
4. Click Add Role. 
5. Select between Edit or View in the permission field.
6. After creating new user roles, navigate to the user list and assign the appropriate roles to the users.

Where: HOME / <project name> / Project Settings / Users