Set up your Microsoft 365 sign-in for multi-factor authentication - Microsoft Support
External users having issues with organizational and microsoft accounts - Microsoft Community Hub
Differences between "MS Account" and "Organizational Account" when sharing with external users - Microsoft Community Hub
How to login to PowerBI Commuity using personal account. - Microsoft Community Hub
Manage organizations for a work or school account in the My Account portal - Microsoft Support
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Setting up Windows 10 for Office 365 users - Microsoft Community