I have these settings:
This example get token thouth HttpWebRequest
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(pathapi);
request.Method = "POST";
string postData = "grant_type=password";
ASCIIEncoding encoding = new ASCIIEncoding();
byte[] byte1 = encoding.GetBytes(postData);
request.ContentType = "application/x-www-form-urlencoded";
request.ContentLength = byte1.Length;
Stream newStream = request.GetRequestStream();
newStream.Write(byte1, 0, byte1.Length);
HttpWebResponse response = request.GetResponse() as HttpWebResponse;
using (Stream responseStream = response.GetResponseStream())
{
StreamReader reader = new StreamReader(responseStream, Encoding.UTF8);
getreaderjson = reader.ReadToEnd();
}