When trying to use Microsoft 365 etc. of EES benefits,

Your IT department has turned off signup for (…). Contact them to complete signup.

If the error is displayed, please check the following.

• Have you signed up for EES benefits using your @u or @un address?
• Is the email address displayed in My Account > Personal Information @u or @un?
  • If you were signed in with another Microsoft account, such as @s, sign out, close your browser, and try again.

Reference:
Online class guidance