Configuring Mapillary Widget V4.0.5 for ArcGIS Enterprise

We’ve just added the widget to our Enterprise’s custom widget pool and we’ve registered a new app with Mapillary. Adding the client keys and organization ID to the widget config seems to work and the sign-in process appears to authenticate. The issue is after approving access, the auth window doesn’t kick anything back to the main app, it just loads the redirect URL. Is there a special URL we need to enter to get this working with an Enterprise deployment? I noticed options for a proxy URL but the links in the config page lead to a github repo that is officially out of support so I’m hesitant to add that to our server.

To be clear: we’re using this with the built in Web AppBuilder, not a developer edition deployment.