downloading file, saving on android

Im trying to download and save a file using WWW. This is working fine in the editor on windows, havent tested mac or ios yet but its not working on android. The file doesnt turn up in com.name.app/files folder. am i missing something here?

 private IEnumerator TestDownload()
     {
         WWW www = new WWW("http://192.168.1.6/file_drop/zipped_file.zip");
         //yield return www;
             
         while (!www.isDone) {
             progress = "downloaded " + (www.progress*100).ToString() + "%...";
             yield return null;
         }
             
         string fullPath = Application.persistentDataPath + "/zipped_file.zip";
         File.WriteAllBytes (fullPath, www.bytes);
             
         progress = "downloaded, unzipping...";
         
 ...
 }