This site is being deprecated.
Please see the official X‑Plane Support page for help.
You will find the X-Plane 10 installer on this page. Your key should work with it and the X-Plane 11 installer to download each version.
Yes, you will get access to download and install both X-Plane 10 & 11 if you buy the digital download product currently offered on X-Plane.com.
This site is no longer being actively maintained.