C-Sharp Daten von PHP lokal speichern

header("Cache-Control: public");  
		header("Content-Description: File Transfer");  
		header("Content-Disposition: attachment; filename=$targetPath");  
		header("Content-Type: application/zip");  
		header("Content-Transfer-Encoding: binary");  

		readFile($targetPath);
			$file_content =  file_get_contents($targetPath);
			echo $file_content;
				exit();

// Formuliert Serveranfrage
            var client = new RestClient("https://....com/test/");  
            var request = new RestRequest("server.php", Method.POST);  
            request.AddParameter("ac", "jdl");  
            request.AddParameter("id", user_id.ToString());  
            request.AddParameter("filename", Path.ChangeExtension(Daten, ".zip"));  
            byte response = client.DownloadData(request);

            // Speichert empfangene Serverdaten
            File.WriteAllBytes(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments), "Server.zip"), response);  
            Directory.CreateDirectory(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "Testorder Server"));  
            ZipFile.ExtractToDirectory(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments), "Server.zip"), Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "Testorder Server"));