C# exception while creating txt file on Google drive

using System;
using Google.Apis.Auth.OAuth2;
using Google.Apis.Drive.v3;
using Google.Apis.Services;
using System.Collections.Generic;
using System.IO;
using System.IO.MemoryMappedFiles;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace ConsoleApp1
{
    internal class Program
    {
        static async Task Main(string[] args)
        {
            ;
            var credentials = await GoogleCredential.FromFileAsync("key/mobileprice-389203-a6dc6ada2693.json", CancellationToken.None);
            var service = new DriveService(new BaseClientService.Initializer());
            Console.WriteLine("success");
            var metadata = new Google.Apis.Drive.v3.Data.File() { Name = "myfile.txt" };
            //var mediacontent = new MemoryStream(System.IO.TextWriter("hello world"));
            //var uploadRequest = service.Files.Create(metadata, mediacontent, "text/plain");
            var uploadRequest = service.Files.Create(metadata);
            uploadRequest.Fields = "id";
            var file = uploadRequest.Execute();
            Console.WriteLine($"File ID: {file.Id}");
            Console.ReadKey();
        }
    }
}

Exception:
service drive exception http status code is un authorise request is missing required authorisation credential expected auth2 access token