Getting Facebook Code+AccessToken In Identity server 4

Question

I have a Identity Server 4 setup using Facebook for authentication. This is very plug and play

.AddFacebook("facebook", options =>
            {

                options.SignInScheme = IdentityServerConstants.ExternalCookieAuthenticationScheme;

                options.ClientId = "xxx";
                options.AppSecret = "xxx";
            });

I can see that during the authentication I am recieving the code needed to request the access token, I'm struggling at how to get this code (or the accesstoken) during the login process, I have a list of all the claims just no tokens.

I've searched a lot regarding this and https://andrewlock.net/ is helpful but he doesn't state how he got this code.