Late answer but if you try adding new users to G Suite, the new user will get that same error when attempting to access email.
This looks like a new development since users created in the past didn't experience the same issue
To resolve, just go to the admin console and manually assign a G-Suite license to the new user.
A user with a similar issue asked the question on this forum here but unfortunately some busybodies closed the issue even before it was resolved.
Hope this will assist someone facing similar problem without having to waste a whole day as I did