A non-profit grant expiration

I don't how to search research .. I received a message that my grant for Microsoft 365 is expiring. When I try to sign in I receive a message that I don't have permission to manage the page. I haven't a clue how to update/manage or find a grant that would work for my organization. I didn't set up the account and can't find a number to call. SO if I can't explain my issue I can't find the answer on their Q & A