To use cloud services such as Teams, Stream, and OneDrive for Business, or to use Office apps for personal use, you must sign in with an @u or @un account, as stated in “Microsoft Products (for private use)“.
Please first check the following:

• Is the email address displayed in “My Account > Personal Information” an @u or an @un one?
  If you were signed in with another Microsoft account, such as @s, then sign out, close your browser, and try again.

In addition, please refer to the following information.

• Zengaku Computer System: About @s address and @u address
• Frequently Asked Questions: “Calendar” icon in MS Teams does not appear

If the issue still persists, please take a screenshot of the error screen and contact us via the EES / Microsoft 365 Inquiry Form.

To use cloud services such as Teams, Stream, and OneDrive for Business, or to use Office apps for personal use, you must sign in with an @u or @un account, as stated in “Microsoft Products (for private use)“.
Please first check the following:

• Is the email address displayed in “My Account > Personal Information” an @u or an @un one?
  If you were signed in with another Microsoft account, such as @s, then sign out, close your browser, and try again.

In addition, please refer to the following information.

• Zengaku Computer System: About @s address and @u address
• Frequently Asked Questions: “Calendar” icon in MS Teams does not appear

If the issue still persists, please take a screenshot of the error screen and contact us via the EES / Microsoft 365 Inquiry Form.