Loadiine expects a specific folder path on your SD card: SD:/wiiu/games/Mario Kart 8 [AMKE01]/ (The base game)
The "AOC" (Add-On Content) folder from your rar file should be placed inside the main game directory. It must contain the code , content , and meta folders for the DLC to be recognized. Important Considerations MK8-USA-DLCs-LOADIINE-ZIPERTO.rar
This specific DLC pack is intended for the original Wii U version . If you are looking for tracks for Mario Kart 8 Deluxe on the Nintendo Switch, these files will not work. Loadiine expects a specific folder path on your