Embedded vRealize Orchestrator Authentication Provider

I'm configuring the embedded vRO inside vRealize Automation 7 appliance with:

. Default tenant: vsphere.local

. Admin group: vsphere.local\vcoadmins (built-in group)

What user I need to use to login into vRO client?

There is no "vcoadmin@vsphere.local" user and, if I create it, I cannot assign it to the proper group.

Thanks a lot,

D.