RestAPi, Clientsecret, ClientId med Basic Auth

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net.Http;
using System.Net;


namespace HTTP_Test
{
    class program
    {
        static void Main()
        {
            Task t = new Task(HTTP_GET);
            t.Start();
            Console.ReadLine();
        }

        static async void HTTP_GET()
        {
            var TARGETURL = "https://api.*****.se/bananer/v1/health";

            /// The client information used to get the OAuth Access Token from the server.
            string clientId = "***********";
            string clientSecret = "************";
       

           Console.WriteLine("GET: + " + TARGETURL);

            // ... Use HttpClient.            
            HttpClient client = new HttpClient();
        
        var byteArray = Encoding.ASCII.GetBytes(clientId + ":" + clientSecret);
            client.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Basic", Convert.ToBase64String(byteArray));

            HttpResponseMessage response = await client.GetAsync(TARGETURL);
            HttpContent content = response.Content;

            // ... Check Status Code                                
            Console.WriteLine("Response StatusCode: " + (int)response.StatusCode);

            // ... Read the string.
            string result = await content.ReadAsStringAsync();

            // ... Display the result.
            if (result != null &&
            result.Length >= 50)
            {
                Console.WriteLine(result.Substring(0, 50) + "...");
            }
        }
    }
}

<div>
<div id="response">

</div>
<input type="button" class="btn btn-primary" value="Call Web API" onclick="javascript:CallWebAPI();" />


<script>
function CallWebAPI() {
	// New XMLHTTPRequest
    var request = new XMLHttpRequest();
	request.open("GET", "https://api.*****.se/bananer/v1/health", false);
	var clientId = '*************';
	var clientSecret = '*************';
	var encodedData = window.btoa(clientId + ':' + clientSecret);
	var authorizationHeaderString = 'Authorization: Basic ' + encodedData;
	alert(authorizationHeaderString);
	request.setRequestHeader("Authorization", authorizationHeaderString); 
	request.send();
	// view request status
    alert(request.status);
    response.innerHTML = request.responseText;
}

</script>

async function CallWebAPI() {
	alert("running");
  const apiUrl = "*********";
  const clientId = '***********';
  const clientSecret = '*********';
  const encodedData = window.btoa(`${clientId}:${clientSecret}`);
  let headers = new Headers();
  headers.append("Authorization", `Basic ${encodedData}`);

  try {
    const res = await fetch(apiUrl, {
        method : 'GET',
        headers : headers,
    });    
    const data = await res.json();
    console.log(data);
  } catch (err) {
      console.log(err);
  }
};

Source	Protocol	Info
Client	TCP	*Serverport* → 443 [SYN] Seq=0 Win=**** Len=0 MSS=1460 WS=256 SACK_PERM=1
Server	TCP	443 → *Serverport* [SYN, ACK] Seq=0 Ack=1 Win=******* Len=0 MSS=1460 SACK_PERM=1
Client	TCP	*Serverport* → 443 [ACK] Seq=1 Ack=1 Win=**** Len=0
Client	TLSv1.2	Client Hello
Server	TLSv1.2	Server Hello, Change Cipher Spec
Server	TLSv1.2	Encrypted Handshake Message
Client	TCP	*Serverport* → 443 [ACK] Seq=518 Ack=148 Win=******* Len=0
Client	TLSv1.2	Change Cipher Spec, Encrypted Handshake Message
Client	TLSv1.2	Application Data
Server	TCP	443 → *Serverport* [ACK] Seq=148 Ack=569 Win=******* Len=0
Server	TCP	[TCP Dup ACK 72#1] 443 → *Serverport* [ACK] Seq=148 Ack=569 Win=******* Len=0
Server	TCP	443 → *Serverport* [ACK] Seq=148 Ack=1060 Win=******* Len=0
Server	TCP	443 → *Serverport* [RST, ACK] Seq=148 Ack=1060 Win=0 Len=0
Client	TCP	25757 → 443 [SYN] Seq=0 Win=**** Len=0 MSS=1460 WS=256 SACK_PERM=1
Server	TCP	443 →*ServerPort* [SYN, ACK] Seq=0 Ack=1 Win=******* Len=0 MSS=1460 SACK_PERM=1
Client	TCP	25757 → 443 [ACK] Seq=1 Ack=1 Win=**** Len=0
Client	TLSv1.2	Client Hello
Server	TCP	443 →*ServerPort* [ACK] Seq=1 Ack=518 Win=******* Len=0
Server	TLSv1.2	Server Hello, Change Cipher Spec
Server	TLSv1.2	Encrypted Handshake Message
Client	TCP	25757 → 443 [ACK] Seq=518 Ack=148 Win=******* Len=0
Client	TLSv1.2	Change Cipher Spec, Encrypted Handshake Message
Client	TLSv1.2	Application Data
Server	TCP	443 →*ServerPort* [ACK] Seq=148 Ack=569 Win=******* Len=0
Server	TCP	[TCP Dup ACK 11***#1] 443 →*ServerPort* [ACK] Seq=148 Ack=569 Win=******* Len=0
Server	TCP	443 →*ServerPort* [ACK] Seq=148 Ack=1060 Win=******* Len=0
Server	TCP	443 →*ServerPort* [RST, ACK] Seq=148 Ack=1060 Win=0 Len=0