private async void MainWindow_Loaded(object sender, RoutedEventArgs e){txtLog.AppendText($"Ask user to download file.\n");var result = MessageBox.Show("We need to download file.", "Download", MessageBoxButton.YesNo);if (result == MessageBoxResult.Yes){txtLog.AppendText($"Start downloading.\n");this.progressBar.Visibility = Visibility.Visible;var downloader = new SimpleDownloader();var stream = await downloader.RequestHttpContentAsync(ConfigurationManager.AppSettings["uri"],ConfigurationManager.AppSettings["username"],ConfigurationManager.AppSettings["password"]);this.progressBar.Visibility = Visibility.Collapsed;txtLog.AppendText($"Done.\n");var path = SaveFile(stream);txtLog.AppendText($"File path is {path}.\n");Process.Start(path);txtLog.AppendText($"Start process {path}.\n");}}

  <appSettings><add key="uri" value=""/><add key="username" value=""/><add key="password" value=""/></appSettings>

        public async Task<Stream> RequestHttpContentAsync(string uriString, string userName, string password){using (HttpClient client = new HttpClient()){client.BaseAddress = new Uri(uriString);client.DefaultRequestHeaders.Accept.Clear();var authorization = Convert.ToBase64String(ASCIIEncoding.ASCII.GetBytes($"{userName}:{password}"));client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", authorization);client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));HttpResponseMessage response = await client.GetAsync(uriString);if (response.IsSuccessStatusCode){HttpContent content = response.Content;var contentStream = await content.ReadAsStreamAsync();return contentStream;}else{throw new FileNotFoundException();}}}

        private string SaveFile(Stream stream){var filePath = System.IO.Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "installFile.msi");using (var fileStream = new FileStream(filePath, FileMode.Create)){byte[] buffer = new byte[2048];int bytesRead;do{bytesRead = stream.Read(buffer, 0, 2048);fileStream.Write(buffer, 0, bytesRead);} while (bytesRead > 0);}return filePath;}

        private async void MainPage_Loaded(object sender, RoutedEventArgs e){txtLog.Text += $"Ask user to download file.\n";var dialog = new MessageDialog("Do you want to download installation file?");dialog.Commands.Add(new UICommand { Label = "Ok", Id = 0 });dialog.Commands.Add(new UICommand { Label = "Cancel", Id = 1 });var res = await dialog.ShowAsync();if ((int)res.Id == 0){txtLog.Text += $"Start downloading.\n";this.progressRing.IsActive = true;var downloader = new SimpleDownloader();var stream = await downloader.RequestHttpContentAsync("","","");this.progressRing.IsActive = false;var file = await SaveStorageFile(stream);var result = await Launcher.LaunchFolderAsync(ApplicationData.Current.LocalFolder);txtLog.Text += $"Done.\n ";}}