The usual question:
- Do you have BOTH the Addon Manager and the Couatl menu ?
Is the Addon Manager reporting KSDF to be Active ?
You say you purchased it, but nothing in your message says you ever activated it and, in fact, your report of the message saying the scenery is in Trial, seems to confirm this.
However, when in Trial, it should work for 5 minutes, so it's not normal that you don't see the airport when you start there unless, of course, something like an antivirus is preventing the software to run, which is why I asked if you have BOTH the Addon Manager and the Couatl menus, since both modules are required for the scenery to run, and this is totally unrelated to the activation, since they are required even if the scenery is in Trial.