According to the official Nintendo Japan website, buyers of the physical version of Breath of the Wild for Wii U must have more than 3GB of free storage in order to install and play the game. Players may use internal storage or an external hard drive, however devices such as thumb drives will not work.

BotW Switch and WiiU

This comes on the heels of an announcement stating that (without installation) the Wii U version of the game will be 13GB, while the Switch version will be 13.4GB.