During installation, sso requests information from us in the administrator tab. Would it be a problem if we write another user with administrator privileges there? Otherwise, I just need to enter my administrator@vsphere.local user. Why?
vSphere replication registration to vCenter requires SSO administrator credentials. This is required to access to SSO service registrations on vCenter and create solution users vSphere replication.
User needs to be the one with administrator privileges to vCenter Single Sign-On, so you can try adding a user to SSO administrator groups and trying to register it.