Slack app SSO integration issue, unable to get the access code in slack app after successful login

Question

I am trying to integrate SSO with my slack app, I have defined the redirect url in my oAuth server. I am able to login successfully with the valid user credentials, however when it is redirecting back to my slack app after successful login I am able to see the code in the url, but I need that code in my slack app which I am not able to get.

Can someone please help me here, if there is any specific setting needs to be done inorder to read the code from the URL in slack app after successful login ? Thanks !