Okta with custom identity implementation

I have a site which I’m trying to implement OIDC using the Okta platform as a starting IDP. We may connect to other OIDC providers later but that’s where we’re starting. Anyway, the site exists already and has other authentication methods including ASP.NET MVC Identity framework implementation. This has been customized for our particular use cases and so we’re not using the OOB framework classes for Users, Roles, Logins, and Claims. I have run the sample Okta .NET MVC application and it shows my login name after I click the login button. On my site it brings me back to the home page and I do not see my okta username. This leads me to believe it’s not really meshing with the identity implementation on the site.

I guess my question is whether there’s a way to specify which classes and providers need to be used when accepting the OIDC login info?