Right. I think I see the problem.
All freeware downloads will vary to some extent depending on the experience & preferences of the person configuring them. This one is configured like the FSX root directory with sub-folders named Effects, Gauges & SimObjects. This is intended to make installation easier & once you're familiar with the principle no instructions are necessary.
Here's a shot of the extracted file in Windows Explorer.

Note that the "aircraft container" folder you need to install to FSX\SimObjects\Airplanes is the one named
Piper Turbo Arrow IV-G1K hidden deep inside the extracted folder in the Simobjects\Airplanes sub-folder. That's the highlighted folder in my shot.
You should also paste the contents of the Effects & Gauges sub-folders into their corresponding folders in FSX.
Please try it & tell me if that fixed it.