services.AddIdentityServer()
            //.AddDeveloperSigningCredential()
            .AddSigningCredential(Certificate.GetCertificate())
            .AddInMemoryIdentityResources(Config.GetIdentityResources())
            .AddInMemoryApiResources(Config.GetApiResources())
            .AddInMemoryClients(Config.GetClients())
            .AddTestUsers(Config.GetUsers());

new Client
        {
         ClientId = "client",
         ClientName = "client",
         ClientSecrets =
                {
                    new Secret("secret".Sha256())
                },
         RequireClientSecret = false,
         RedirectUris = new List<string>(new string[] { "https://www.getpostman.com/oauth2/callback", "http://localhost:8002", "http://192.168.1.5:8002","app.buyingagent:/oauthredirect"}),
         AllowedGrantTypes = GrantTypes.Code,
         //RequirePkce = true,
         AllowedScopes = { "api" },
         AllowOfflineAccess = true
        }

public static X509Certificate2 GetCertificate()
    {
        using (var store = new X509Store(StoreName.Root, StoreLocation.LocalMachine))
        {
            store.Open(OpenFlags.OpenExistingOnly);
            var certs = store.Certificates.Find(X509FindType.FindBySubjectName, "cert", false);
            return certs.Count > 0 ? certs[0] : null;
        }
    }

POST http://{url}/connect/token
Request Headers:
    undefined:undefined
Request Body:
    grant_type:"authorization_code"
 code:"7cb58d345975af02332f2b67cb71958ba0a48c391e34edabd0d9dd1500e3f24e"
 redirect_uri:"https://identity.buyingagentapp.com/connect/token"
 client_id:"client"
Response Headers:
    undefined:undefined
Response Body:
    error:"invalid_grant"
    invalid_grant
Error