In this case you were probably signed into the other Microsoft/Office 365 Account when you completed the registration. You should make sure you are signed out of all Microsoft Accounts and run the G4MSREGSVC request again, but specify REDO(*YES) on the command. You can sign out of your Microsoft Accounts by clicking here, selecting your account icon (usually at the top right of the screen) and selecting the Sign out option.
If the link takes you to a site asking you to sign into your Microsoft Account you are already signed out and should NOT sign in at this point. You will do select the account when clicking the link that takes you from our website to Microsoft's website so you can accept G4MS to perform the option you need (send email on behalf of, use OneDrive, etc) with the account you are using on the G4MSREGSVC command.