On premises web application and redirect url

I have a issue with redirect_url and a owin web application… I have a web application that is installed on a clients local web server. We are trying to allow them to login to this web application using Auth0 as our universal identity system. The problem is with the redirect_url, with our cloud based web application, setting the redirect_url is simple as there is only the one. However how can this be done for a installed web application? It would be best if I did not have to add something for EVERY installed local web application.
Do we need to add the redirect_url for each installed instance of the web application?
Do we have to have to add a new application for each instance of the installed application?

Is there anyway around this, I was planning on using the implicit flow, so I did not have to have a client secret on each installed web application, but I’m willing to change that if there is a easier path.

Instead of specifying a fixed redirect URL in your Auth0 configuration, you can use a dynamic redirect URL that is determined based on the client’s local web server address.
This way, you don’t need to manually add a redirect URL for each installed instance.

Easy you can configure a single wildcard redirect URL that matches multiple URLs for your installed web applications.
ex:
https://client.localwebserver.com/callback and have it match https://app1.localwebserver.com/callback, https://app2.localwebserver.com/callback

on one word you set wildcard on your DNS something like that https://*.localwebserver.com/callback.

I hope it helps you