Microsoft365.com/setup is an official portal to activate and start your Microsoft 365 product including office apps, cloud services and other collaboration services. You’ll need to Sign In and enter the Microsoft 365 product key.
To see this working, head to your live site.
Go to Microsoft365.com/setup, Microsoft 365 Setup website.
Sign In to your Office Account or Create a New One.
Now Enter Product Key.
Click Install Office Button.
Go ahead and Click Install Office Again.
Save and Run office setup.
Wait for Office to finish Installation.