Error in Zoom CC Web chat client

I'm new to this, and trying to follow a training guide.  I built the flow for a web chat client.  I have connected a domain (an extra one I use for testing) to the Zoom account, and verified it.  I created the entry point, and then added the entry point to the flow.  

I took the java script it created, and embedded it in a simple web page on a web server here on my LAN.  Since the domain involved doesn't currently have any machines in it, I just added an entry for the domain to my windows host file and pointed it at the server.

Opened a browser, and there is the chat button.  I push the button, and it asks me for my nickname and e mail (I'm assuming it does this by default as this isn't part of my script), and hit submit.  The client comes back with the following completely unhelpful error:   Failed to login: The subdomain URL is not connecting. Manage subdomains in Contact Center preferences.

I don't understand.  The domain is verified.  It's listed in the contact center preferences.  I don't need a subdomain as I'm just using the main domain.    How in the world does one troubleshoot this???