How do I import the assets into Unity?
If you didn't purchase the asset on the Unity Asset Store, this is the method to add it to your Unity project.
There's a bunch of errors when I import!
You will see a bunch of import warnings that look like: File 'RPG-Character@Animation-Name' has animation import warnings. See Import Messages in Animation Import Settings for more details. These only show up the first time the animations are imported and don't have any further effect upon the project.
Can I use the animations in UE4?
Yes. You'll need a copy of Unity to be able to open and extract the .unitypackage file to get the .fbx files. See the above video for instructions extracting the asset to get the .fbx files.
Can I use the FREE assets in commercial products?
Yes you can. There's no requirement to link or credit the animations, but it would be nice. :)