I am trying to navigate to the sign up page at https://api.einstein.ai/signup - it brings me to the page to sign up using salesforce (or Heroku).  I am clicking on the sign up using Salesforce.
I click on the Allow access - and get "An error occured while serving your request" email already registered. 
How do I get around this to be able to download the private key needed ?

For the trailhead 'Get an Einstein Platform Account' i got to the download the key button but i tfailed to save anything at all, is there any other way to get this key? Currently when i try again it says my email is already registered?