Okta Authorization Server


I am implementing sitecore identity for intranet site using Okta… The challenge I am having is the identity provider does not redirect me to Okta login page and I am not getting any error either although my custom identity provider code get hit.
Following are my Okta settings for identity provider processor: Also can you please guide for callback handling url (identity/externallogincallback) after Okta authentication, do I need to write some handler/code or it will be handled/redirected to the identity provider processor with authorization code.