How to download files from Google drive and save to a folder on local using C#

private bool SaveToDir(string downloadUrl,string filename) {
string filePath = Server.MapPath("imports/");
bool resp = false;
DriveService ds = new DriveService();
Uri temp = new Uri(downloadUrl);
string fileId = HttpUtility.ParseQueryString(temp.Query).Get("id");
var req = ds.Files.Get(fileId.Trim());
var stream = new MemoryStream();
req.MediaDownloader.ProgressChanged += (Google.Apis.Download.IDownloadProgress dp)=> {
switch (dp.Status)
{
 case Google.Apis.Download.DownloadStatus.Downloading:
      Message("downloading, please wait....");
      break;
 case Google.Apis.Download.DownloadStatus.Completed:
      using (FileStream file = new FileStream(filePath, FileMode.Create, FileAccess.Write))
            {
                stream.WriteTo(file);
                Message("File Downloaded successfully.");
            }
      resp = true;
      break;
 case Google.Apis.Download.DownloadStatus.Failed:
      Message("Failed to Download.");
      resp = false;
      break;
 }
 };
 req.Download(stream);