This site is being deprecated.
Please see the official X‑Plane Support page for help.
It sounds like your internet connection is cutting out mid-download.
This is in the installer, or within X-Plane itself?
If the installer, please upload your "X-Plane Installer Log.txt" that appears on your desktop after you've exited.
If this is within X-Plane itself, try downloading the installer directly from the web site.
This site is no longer being actively maintained.