student data files 2018

I downloaded the student data files, premium full version 2018.  I was working thru chapter 1 and realized I needed the backup files downloaded.  So I did that and typed "y" to overwrite existing files.  Now I have no "SAI" files to go onto chapter 3.  I've deleted my existing download and reinstalled from the student DVD only the full premium version and still no SAI files.  What have I done incorrectly.

Regards, Lura