Go through microsoft365.com/setup webpage, Sign in, and enter the product key to download and install Microsoft 365 or Office on your computer. If you are using any other Microsoft service such as OneDrive, Outlook.com, Skype, or Xbox Live, it means you already have an account that you can use for any Microsoft activity. To download Microsoft 365 setup, go to microsoft365.com/setup and follow instructions.
https://sites.google.com/site/microsoft365comsetup/microsoft365-com-setup