i have a problem with authentication it says i am unauthenticated
I have already tried like pben in the example to specify username and password but I get no authentication.
Here is another link to the authentication page of the mobile.de site
https://services.mobile.de/docs/seller-api.html#_authentication_and_authorization
    let url = 'https://services.mobile.de/seller-api/sellers/sellerid/ads';
    let username = 'username';
    let password = 'password';
    
    let headers = new Headers();
    headers.set('Authorization', 'Basic ' + base64.encode(username + ":" + password));
    fetch(url, {method:'GET',
      headers: headers,
    })
        .then(response => console.log(response))
i get this in my Console
        Response {
      size: 0,
      [Symbol(Body internals)]: {
        body: PassThrough {
          _readableState: [ReadableState],
          _events: [Object: null prototype],
          _eventsCount: 5,
          _maxListeners: undefined,
          _writableState: [WritableState],
          allowHalfOpen: true,
          [Symbol(kCapture)]: false,
          [Symbol(kCallback)]: null
        },
        stream: PassThrough {
          _readableState: [ReadableState],
          _events: [Object: null prototype],
          _eventsCount: 5,
          _maxListeners: undefined,
          _writableState: [WritableState],
          allowHalfOpen: true,
          [Symbol(kCapture)]: false,
          [Symbol(kCallback)]: null
        },
        boundary: null,
        disturbed: false,
        error: null
      },
      [Symbol(Response internals)]: {
        type: 'default',
        url: 'https://services.mobile.de/seller-api/sellers/mobileID/ads',
        status: 401,
        statusText: 'Unauthorized',
        headers: {
          connection: 'close',
          'content-length': '0',
          date: 'Thu, 06 Oct 2022 23:52:28 GMT',
          'www-authenticate': 'Basic realm="mobile.de api"'
        },
        counter: 0,
        highWaterMark: 16384
      }
    }
    Response {
      size: 0,
      [Symbol(Body internals)]: {
        body: PassThrough {
          _readableState: [ReadableState],
          _events: [Object: null prototype],
          _eventsCount: 5,
          _maxListeners: undefined,
          _writableState: [WritableState],
          allowHalfOpen: true,
          [Symbol(kCapture)]: false,
          [Symbol(kCallback)]: null
        },
        stream: PassThrough {
          _readableState: [ReadableState],
          _events: [Object: null prototype],
          _eventsCount: 5,
          _maxListeners: undefined,
          _writableState: [WritableState],
          allowHalfOpen: true,
          [Symbol(kCapture)]: false,
          [Symbol(kCallback)]: null
        },
        boundary: null,
        disturbed: false,
        error: null
      },
      [Symbol(Response internals)]: {
        type: 'default',
        url: 'https://services.mobile.de/seller-api/sellers/mobileid/ads',
        status: 401,
        statusText: 'Unauthorized',
        headers: {
          connection: 'close',
          'content-length': '0',
          date: 'Thu, 06 Oct 2022 23:52:28 GMT',
          'www-authenticate': 'Basic realm="mobile.de api"'
        },
        counter: 0,
        highWaterMark: 16384
      }
    }
I have only worked with Directus RestAPI before.
 
    