Ai traffic consists, concretely, in two things:
- aircrafts, with appropriate repaints for the real-world companies
- traffic files, which are in fact scenery files, with ".BGL" extension.

The aircraft folders, you can simply put them into your simobjects\misc folder.
The traffic files, you have to put them into the Scenery\world\scenery folder.

That's pretty much all you need to do, normally
I don't know about the package you have downloaded, so I don't really know how are the things presented inside. But normally, the readme should explain you where to put what.