Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
OK, sorted.
I had to change the properties of my Azure AD user to belong to another domain (an "onmicrosoft" one) which was visible on the office portal but not in the drop-down on the AD Connect wizard locally.
Once this was done and the wizard was re-started, everything worked as it should.
To say this is confusing would be a bit of an understatement.