The Contributor and Moderator roles are internal roles reserved for employees or other organization members with a paid seat in your Workspace. If you would like a user to have one of these roles, invite them to your Workspace via the Admin Console.
Once they've accepted your invite, by default, their role will be changed to Contributor within any Circles that they belong to in your Workspace, and you can the upgrade them to Moderator if desired.
Professionals & Consultants
The Professionals & Consultants plan is intended for a single consultant or professional user and does not provide the option to invite others. If you work for an organization and will require more than one seat for your use case, a Teams & Business or Education & Nonprofit plan would be more appropriate for you.
Upgrade to an Education & Nonprofit Premium Plan