"Unknown extension "uasset"

I recently got my hands on Shooter game demo I found on random website since its not available on marketplace for me anymore.
I managed to get my hands on It’s content but im having problems adding it to my UE.

I tried copy pasting files to project’s folder but that breaks the project.
I also tried drag and drop technic but that gives me error mentioned in the title.

Please help, I really want to take a closer look at this models.

Version of UE4: 4.8.1
Demo version:

Hi Texas-Doughnut -

The Shooter Game Demo is on the Launcher under the Learn Tab toward the bottom under Example Game Projects. I would recommend downloading from the Launcher in the version of the engine you are currently on.

Thank You

Eric Ketchum