Demystifying Exchange Online Provisioning: Architecture, Exchange Object Types, and Attributes

Brian Gallup Thanks for your comment.

If you have an Exchange hybrid environment, you should always provision the mailboxes from your on-premises organization.

In my opinion you're doing too many steps that would lead into possible validation errors at some point, and you should do this instead:

- Create a new remote mailbox (this will create the user in local AD with the remote mailbox properties directly) and enable the remote archive. Once the user is synced you will have the primary and archive mailboxes provisioned in Exchange Online.

- At this point the mailboxes are provisioned in Exchange Online and no need to set the ArchiveGuid in on-premises (as it will be already generated from on-premises), and you should just need to assign the license in Office 365 admin center.