Custom web site registered in Portal requires login

[PLadd]

I created a basic web app using ArcGIS Enterprise Portal, shared it with Everyone, and it works fine. 

I want to customize it on my own (Web AppBuilder <Developer Edition> wasn't cutting it for me) so I  downloaded the new site from Portal to my server.

In IIS I used “Convert to Application” and hosted the downloaded site from my own server.  When I browse to the site, I’m asked for my ArcGIS Enterprise credentials, which I provide and the site on my server works just as well as the one on my Portal. 

But I want the app to be available to the public without a login. 

Here's what I've tried:

• In Portal > Content > New item > Application > Web mapping I added the custom application and registered it. 
• I shared my custom app with Everyone.
• I made sure the web layer the app is consuming is shared to Everyone. 
• I copied the registered appID to the config.json file at the root of my custom app

I'm still getting the ArcGIS Enterprise popup:

Google search didn't provide any direction.

Does anybody know if it's even possible for me to take this custom app that I've downloaded and registered in Portal and have the public access it without being asked for credentials?  

Thank you!

[PLadd · Accepted solution]

Turns out it was a PICNIC (Problem In Chair Not In Computer). 

I hadn't shared the map layers with the public.