I have problems sending my credentials and consuming an API

I already managed to solve my question about the token, now what I have problems is how I can upload a file of txt format that I have saved on my disk D in a folder called SENDSUNAT \ doc.txt once I return that, I generate a ticket to which I concatenate it and they will return me 3 xml, zip and excel files that I want to save in a different folder ... Could someone help me?

    //VARIABLES
    const string userName = "mi usuario";
    const string password = "mi clave";
    const string apiBaseUri = "https://ose-gw1.efact.pe:443";
    const string apiGetPeoplePath = "/api-efact-ose/oauth";
    const string authorization = "Y2xpZW50OnNlY3JldA==";
    const string tempurl = @"D:\SENDSUNAT\doc.txt";
    const string tempurl2 = "doc.txt";

    static void Main(string[] args)
    {
        //OBTENER EL TOKEN
        var token = GetAPIToken(userName, password, apiBaseUri).Result;
        Console.WriteLine("Token: {0}", token);

        //HACER EL LLAMADO
        var response = GetRequest(token, apiBaseUri, apiGetPeoplePath).Result;
        Console.WriteLine("response: {0}", response);

        //ESPERAR LA CLAVE
        Console.ReadKey();
    }

    private static async Task<string> GetAPIToken(string userName, string password, string apiBaseUri)
    {
        using (var client = new HttpClient())
        {
            //SETUP CLIENTE
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", authorization);
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            //SETUP LOGIN DATA
            var formContent = new FormUrlEncodedContent(new[]
            {
                new KeyValuePair<string, string>("grant_type", "password"),
                new KeyValuePair<string, string>("username", userName),
                new KeyValuePair<string, string>("password", password),
            });

            //ENVIAR REQUEST
            HttpResponseMessage response = await client.PostAsync("https://ose-gw1.efact.pe:443/api-efact-ose/oauth/token", formContent);


            //OBTENER EL ACCESO TOKEN DEL RESPONSE BODY
            var responseJson = await response.Content.ReadAsStringAsync();
            var jObject = JObject.Parse(responseJson);
            return jObject.GetValue("access_token").ToString();
        }
    }

    static async Task<string> GetRequest(string token, string apiBaseUri, string requestPath)
    {
        using (var client = new HttpClient())
        {
            //SETUP CLIENTE
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            client.DefaultRequestHeaders.Add("Authorization", "Bearer " + token);

            //var cont = new MultipartFormDataContent();
            //cont.Add(new StreamContent(new MemoryStream()), "file", tempurl);

            //var cont = new MultipartFormDataContent();
            //var fileContent = new ByteArrayContent(System.IO.File.ReadAllBytes(tempurl));
            //cont.Add(fileContent);

            //var cont = new ByteArrayContent(System.IO.File.ReadAllBytes(tempurl));
            //Stream fileStream = System.IO.File.OpenRead("D:\SENDSUNAT\" + tempurl2);

            //var cont = new MultipartFormDataContent();
            //cont.Add(new ByteArrayContent(File.ReadAllBytes(tempurl)));

            //var cont = new MultipartFormDataContent();

            var method = new MultipartFormDataContent();
            const string fileName = "D:\SENDSUNAT\doc.txt";
            var streamContent = new StreamContent(File.Open(fileName, FileMode.Open));
            method.Add(streamContent, "file");

            //HACER EL REQUEST
            HttpResponseMessage response = await client.PostAsync("https://ose-gw1.efact.pe:443/api-efact-ose/v1/document", method);
            var responseString = await response.Content.ReadAsStringAsync();
            return responseString;
        }
    }