: If using an external drive, plug it into the Wii U and format it via System Settings > Data Management . Prepare the SD Card : Create a folder named install on the root of your SD card.
This runs decrypted games directly from the SD card. It is often slower than USB but useful for quick testing. How to Format an External Storage Device - Nintendo Support New Super Luigi U WII U ISO (Loadiine & USB) (USA)
To play on a modded Wii U, you typically use either Loadiine GX2 (for SD card loading) or WUP Installer GX2 (for installing directly to the Wii U Menu/USB). Method 1: USB Installation (Recommended) : If using an external drive, plug it