In those few steps I’ll show how to install UE4 content pack.
Download an asset package from the website.
Unpack downloaded archive using provided password.
Open your UE4 project folder and navigate to Content sub-folder.
Note: At This stage it is recommended to close Unreal Engine Editor.
Copy M_Orzelek_Assets folder and paste it to Content sub-folder.
Note: Each asset package has an UE4 folder in it. A Source folder with Mesh and Textures can also be found in some of the packages.
It is done. Your new assets should be available in content browser.
If you have any questions or suggestions feel free to comment.