If you get a message saying “error reading setup initialization file” while you are trying to run the installer, probably something went wrong with your download, and you didn’t actually get the full installer.

Try downloading the installer again.  If you are prompted to “Run from here” or “Save to disk”, save to disk.  Wait for the download to complete, and after it has completed, run the newly downloaded copy of the installer.

If you get the same problem, check the file size of the file, and compare it to the size that is listed on the software download page.  Keep trying to download until you get the full installer.