Android path problems

Hello everyone. I've got simple app, and it works fine on my PC. But on my Android-Testing Device it can not work properly. Something wrong with the paths. For Android I'm using the code to get files I want to read/write from StreamingAssets to Application.persistentDataPath:

 void Awake(){
 if (firstWord == "Adroid" || deviceType == "Handheld")
         {
             StartCoroutine("Downloader");
         }           
 }
 
 IEnumerator Downloader()
     {
         WWW wwwDD = new WWW("jar:file://" + Application.dataPath + "!/assets/DropDown.xml");
 
         yield return wwwDD;
 
         if (wwwDD.isDone == true)
         {
             File.WriteAllBytes(Application.persistentDataPath + "/DropDown.xml", wwwDD.bytes);
         }
 
         WWW www1st = new WWW("jar:file://" + Application.dataPath + "!/assets/1st.xml");
 
         yield return www1st;
 
         if (www1st.isDone == true)
         {
             File.WriteAllBytes(Application.persistentDataPath + "/1st.xml", www1st.bytes);
         }
 
         WWW wwwDefault = new WWW("jar:file://" + Application.dataPath + "!/assets/Default.xml");
 
         yield return wwwDefault;
 
         if (wwwDefault.isDone == true)
         {
             File.WriteAllBytes(Application.persistentDataPath + "/Default.xml", wwwDefault.bytes);
         }
     }

And in logcat I've got error:

 UnauthorizedAccessException: Access to the path '/data/data/<my project>/files/' is denied.

Write Access is set to Internal, and if I change it to External and add to AndroidManifest.xml:

 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

I get the same problem.

What am I doing wrong? Please tell me, I haven't sleep for about a week trying to solve this