Cannot get Access Token via https://api.dropboxapi.com/oauth2/token!

When I try to get an access Token using Fetch in JavaScript via the in the title specified endpoint, it returns this:

{"webSocket":null,"url":"https://api.dropboxapi.com/oauth2/token","redirected":false,"ok":true,"headers":{},"statusText":"OK","status":200,"bodyUsed":false,"body":{"locked":false}}

My Code is this:

    async function getInitial() {
      let dropBoxConnection = await fetch(`https://api.dropboxapi.com/oauth2/token`, {
        body: new URLSearchParams({
          code: dropToken,
          grant_type: 'authorization_code',
          redirect_uri: DropBoxData.redirect,
          client_id: DropBoxData.key,
          client_secret: DropBoxData.secret
        }),
        method: "POST"
      }).then((response) => {
        return response;
      }).catch((error) =>  {
        return new Error(error);
      });

      return await dropBoxConnection;
    }

    if(dropToken) var DropboxReturn = await getInitial();

    return new Response("Old Token: " + dropToken + ";" + " API-Response: " + JSON.stringify(DropboxReturn));