Dashboard Authentication "No route was found matching the URL"

When adding WPMU DEV Dashboard to an old site and got to authenticate, I enter email and password to register the dashboard, I get the following:
URL: https://premium.wpmudev.org/api/dashboard/v1/authenticate

{"code":"rest_no_route","message":"No route was found matching the URL and request method","data":{"status":404}}

I have un-installed and re-installed with the same results.
site: http://intheflow.us