Could I please get some clear instructions on how to install this airport?
You run the installer.
Part of me wonders if these crashes are because I had so many issues installing it.
Which issues ?
First off I wasn't aware that I needed a separate program called addon manager first
You don't. It obviously come with the installer, which installs everything needed automatically.
then I installed this airport, but the installar kept pointing it to a folder called addon manager.
And why you think this would be a problem ?
After that the airport wouldn't display in the sim so I manually copied all the files contained in addon manager folder to the root of my p3d directory since the folder structure made it seem like that's where it belonged, and furthermore that's what I had to do to even get the airport to display in the sim.
And by doing this, you probably caused a whole big mess. You cannot just copy stuff that way, why you think there are installers ? They don't "just" copy files, there are permission issues to deal with, registry entries to set, and lots of other stuff.
For example, our installer needs to store a registry key to set its installation folder, which is then read by the software to set all its proper running path. The key is set by the installer but, if you move files manually elsewhere, nothing will then work.
I think it would be best if you simply Uninstall everything, including the P3D4, clear its folder, because it would be the only way to be sure this will undo any mess you have created by moving files manually, then reinstall P3D and reinstall KCLT and DO NOT TOUCH ANYTHING.
Don't assume the installer is wrong or bugged. The installer knows what to do. If it suggest to install into C:\Program Files (x86)\Addon Manager, it's because it's usually a good place to install into, like any other Windows software out there. The only reason why you would want to change that, if if you know you are low on disk space on C: