WordPress Migration Can't Connect to DB

I am trying to use the Auth0 plug-in for WordPress using the user migration option but having no luck. I spent an entire day trying to make this work. I have installed the plug-in and configured as described here: User Migration in Login by Auth0 WordPress Plugin

I have verified the endpointUrl and migrationToken in the Auth0 configuration many times. I copied the login script from the GitHub repository as instructed. But when I click “Save and Try” I always get “Unexpected token < in JSON at position 0”. This is the main site of a WordPress multisite implementation and it is the first I have installed the plugin on.

I am at my wit’s end here, what can I do to resolve this? The troubleshooting steps indicate that this is a problem with the endpoint, but I have verified the endpointUrl and migrationToken are correct so what else could it be?

We have resolved this. The issue is that our WordPress dev and stage sites are password protected. When we looked at the complete response string being returned by the Auth0 plugin endpoint, we saw that it is the HTML for the password dialog. We had to disable the password protection in WordPress Engine and then the database scripts worked as expected. Posting the resolution here in case some one else runs into this.