Services cannot be assigned directly to a user nor can a user be assigned directly to a service.

If you have organized your organization into mailboxes , you can assign services and add users to each mailbox. All users who are part of it will be able to access and work in the services associated with that mailbox.

If you don't use mailboxes , no assignment is necessary: all users will have automatic access to all available services, without the need to assign them.

Only if you choose to Use mailboxes in the entity , you add users and assign services to specific mailboxes that you have created. If you do not use mailboxes, no assignment is necessary, as all users will have access to all available services.