Hello Bill, this is Henry.
First, your old email tied to the Volume Licensing account is blocking progress. You should contact Microsoft Volume Licensing Support to verify your nonprofit’s identity and assign a new admin email.
Once access is restored, contact TechSoup or a Microsoft partner to buy the ESU license. The key will appear in your M365 Admin Center.
After you get the key, please run these commands in Command Prompt as Administrator:
-
slmgr /ipk <your ESU key> -
slmgr /ato
Then verify with: slmgr /dlv
Look for confirmation that the ESU license is active.