Thanks for the response.
The behavior that is problematic is when user@gmail.com, who has a free cloud account, is not logged into that account and pastes the generated url into a browser (I have tried Safari, Chrome, and IE).
A Sign-in screen appears and I fill in the required credentials and click "Sign-In": 
However, the "Hello" page is not returned. Rather I get this error page: 
Interestingly, I have realized that this action has in fact logged user@gmail.com into his Wolfram Programming Cloud account. So that next time the url is run in the browser "Hello" appears in Programming Cloud desktop.

My preference is to have the user be able to cleanly log into my cloud application without having previously logged into his cloud account.
Is this possible.