Sorry! Microsoft To-Do is not enabled for your organization.
Doesn't appear to be available for my personal O365 tenant, as I received the message above. Tried the web app with my work tenant, but couldn't get logged in... get a 501 error, most likely due to our 3rd party single sign-on.
Please look here for supported accounts – https://todosupport.helpshift.com/a/microsoft-to-do/?l=en&p=all&s=setup&f=system-requirements-and-supported-accounts
Yes, I have the same problem as @Matt Rogers: We have an education account. It works fine with the mobile app but the web app gives a 501 error and says that it is not supported for Education - which is wrong.
Matt Rogers commented
I also get a 501 error on the webapp, and I manage a professional Office 365 org with Enterprise E5 licenses. I can log in on the mobile app, but the webapp fails.
Steffen Nye commented
appears to be turned off for my work tenant as well.