I am trying to create a form that prompts for a Password. When entered correctly it should send the user to a Thank You page

Hello, unfortunately we do not really allow password fields  and usernames. It violates our Terms of Use as this kinds of forms had been extensively abused by some of our users to conduct phishing or other illegal activities.

If you chose to create such forms, please be advised that your account may end being suspended. Thank you for your cooperation.

However, you allow / disallow access using conditions. Please read the instructions with example 

Hope this helps.