I am trying to complete the Trailhead item to Build a Cat Rescue App, but I'm getting stuck at the Install Einstein Vision Apex Wrappers unit.  I have created an Einstein Platform Account and received the "welcome aboard" email, and have installed the third-party package and set up the email as per the trail instructions.  However, when I click to verify the step I get a "System.NullPointerException: null argument for JSONGenerator.writeStringField()" error.

I've searched the forum on this error, and each post states this is the result of not putting in the proper email.  I have already confirmed that the email address I have put into the Email item in custom settings is the same email that received the "welcome aboard" email when I set up the Platform account.  I repeat, this is not due to an incorrect email entered into the custom settings as I have confirmed I have entered the same email address that got the welcome aboard email from the Salesforce Einstein Team.

Does anybody know what could be causing this error?  I have also tried deleting and re-installing the package.  I have installed for System Admins only and for All users, still getting the same error.  I have also tried installing it using an incognito error, with no resolution.  Any assistance would be much appreciated!!