Connecting SharePoint to Azure

To assign your primary account, email address removed for privacy reasons, its own SharePoint drive, ensure it has an active Microsoft 365 license that includes SharePoint Online and OneDrive for Business. Only licensed member accounts, not guest accounts, receive a personal OneDrive. Once licensed, either sign in once to OneDrive or have an admin pre-provision it so the drive becomes available. Then, you can attach SharePoint libraries to it using Sync or add a shortcut to OneDrive inside the library.

The reason your other account, edwin@onmicrosoftaccount, can use the OAuth app is that apps are tied to the Azure AD or Entra tenant, not just the UPN you used to register them, and by default, app registrations can be multitenant, meaning they accept logins from any organizational directory unless you specifically set them to single tenant. If both UPNs are in the same tenant, then any account in that tenant can access the app once consent is granted. If you want strict isolation, go into the app registration in Entra ID and set the supported account types to single tenant. Then, adjust the enterprise app consent settings so that only admins can grant the app’s requested Graph or SharePoint permissions, which will prevent other tenants or unintended accounts from connecting.