The keyword "work" depends on your platform:
: It begins "packing" those .app files into the official Wii U file system. Because it uses official installation APIs, the console treats the finished product exactly like a game bought from the eShop. From Disc to Digital wii u wup roms work
The app reads the .tmd and .tik files to understand how to unpack and "install" the .app data directly onto the Wii U’s internal storage (NAND) or an external USB hard drive. The keyword "work" depends on your platform: :