Thank you for posting this in Microsoft Q&A.
I'm sharing this screenshot to ensure that we are on the same page and that you are encountering the same error that I have.
Could you please confirm the role assigned to your account and whether the account type is Guest or Member?
The error message indicates that you do not have the necessary permissions and that a Guest user account might be used for the configuration.
For Microsoft Entra Cloud Sync, a Hybrid Identity Administrator or Global Administrator permission is required, and the account type must be Member, not Guest.
For your reference: Prerequisites for Microsoft Entra Cloud Sync
Hope this helps. Do let us know if you any further queries.