Hey FarukC,
The module for working with additional assets shows how you can use your own assets with Unreal Engine 5. The files shown are some sample files that we chose to show how these types of assets can be imported and what you might see when you import them.
You can use any of your own assets to follow along if you would like, otherwise, you can watch the video and see how you would import when you need it.
If you do need some assets, there are some sample ones included with the project in a .zip file in the Content directory. I have attached a screenshot showing the folder where the file is (mine is in my Projects folder) as well as the name (RawAssets.zip). You can extract these to another location on your computer and use them if you would like to follow along with when watching the module.
-Matt, Epic Online Learning
