This site is being deprecated.
Please see the official X‑Plane Support page for help.
First I want to double check you got an X-Plane 9 installer and not the v10 installer. The welcome screen (initial screen) of the installer should tell you want version it's for.
The v9 updater is located here. It looks like you might need to use the installer on the discs and then use that updater to get the latest version of v9.
This site is no longer being actively maintained.