Mixed authentication using ASP.NET Identity and Auth0

Hi guys!

I am implementing Auth0 in a Episerver CMS using ASP.NET (OWIN).

In the solution, there are two websites.
https:// xxx.com (public website)
https:// xxx.portal.com (intranet, e.g for reseller to login)

I only want to use Auth0 on intranet and keep using ASP.NET on the the public website,
Is it possible?

The Auth0’s allowed callback and logout urls, I have set https:// xxx.portal.com/callback.

My startup.cs