Writing and Reading Files in Android

I am writing bytes to the device and reading it back to make sure I have saved it:

 var path= Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Personal), filename);
 File.WriteAllBytes(path, bytes);
 var allGood= File.ReadAllBytes(path);

I then browse with the app "ES File Explorer" to the /data/data/CSI.Android/files/ where the file saved, but there is nothing there.

I have added read and write to external storage in the Manifest.

My goal is to use an Intent to open the saved file in a PDF viewer.

Am I missing something?