You choose the experience per client.
You operate. Your team runs setup, ads, and reporting. The client never logs in. Use this when you want a white-glove service.
They log in. You invite people at the client to view or steer that workspace only. They see your brand, not Waverunner. Invites are sent by you. There is no public signup on your domain.
Switch this in the agency console for that client. More detail: Agencies documentation.