Problems accessing external C#API

Question

I am trying to access the Pagseguro API to view the account balance but the following error appears. (I deleted my email and token in the print as well as in the code below).

Document print:

Code on the controller:

string url = String.Format("https://ws.pagseguro.uol.com.br/transfer/balance?email=&token=");

            //Classe que irá fazer a requisição GET.
            HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);

            //Método do webrequest.
            request.Method = "GET";
            request.ContentType = "application/vnd.pagseguro.com.br.v1+json";
            request.UseDefaultCredentials = true;
            request.Proxy.Credentials = System.Net.CredentialCache.DefaultCredentials;


            //Obtém resposta do servidor.
            using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
            {
                //Cria stream para obter retorno.
                using (Stream dataStream = response.GetResponseStream())
                {
                    //Lê stream.
                    using (StreamReader reader = new StreamReader(dataStream))
                    {

                    }
                }
            }

            return View();