Yes. I'm the admin and when I try to run even as admin, it won't open!
Yes, it will. It will just take a bit more with UAC, because Windows itself takes more time to open an installer with UAC on so, you were misled by thinking it "didn't open", but it was just Windows that was making its checks. Without UAC, it's simply faster but, as I've said, is not required.
You only had to wait a bit more but, if you were impatient and double-clicked the installer another time, two copies of it will cause issues of one stopping the other one, so you would be even more convinced the installer "didn't open", because at that point it really stopped.
So you turned off UAC and rebooted Windows, and the reboot what was fixed it, but since you turned off UAC as well, you believed it was the UAC what "fixed" the issue which, instead, was caused by the fact you didn't waited enough time for the installer to launch when UAC was on, and you likely launched another copy of the installer, causing it to be stuck.
Note that this doesn't have anything to do with GSX installer, it can happen with any installer of any product that requires admin rights, so it takes a bit more to start when UAC on.
And is the restoring files from backup normal?
If you are referring to the fact I told you to restore the vehicles_airport.bgl file from the backup a previous GSX install made, it's not normal, but it was required BECAUSE you didn't had the original file anymore, but BECAUSE GSX MADE a backup, you can restore it, the whole point of making a backup is to allow to restore the original file...
And by whatever it means a whole bunch of stuff wasn't installed. Here's a picture...
Again, I don't see anything in your screenshot that would indicate a "problem". Do you have Zurich installed ? Probably not so, it's absolutely normal and obvious the installer would not update its related file.
And besides, have you actually TRIED if GSX WORKS ?