If you know other ways to obtain game file, feel free to use them.
Now create three new folders in Cemu Emulator folder
Download WiiU_Usb_Helper from Here
Step 1 – Launch WiiU_USB_Helper, at the bottom of its window, set the default directories of following:
Step 2 – Now search The Legend of Zelda: Breath of the Wild in Wii U Helper
Step 3 – Select Game (your region specific). Right click the game and select download game (Click no when it asks for DLC and updates)
Step 4 – Right Click on the game again and select Download update and chose V1.76 update.
Step 5 – Right click once again and select download DLC
Step 6 – Now click on start download
Step 7 – When download is complete. Right click game icon and click unpack (loadline) or you can check Unpack option while downloading the files on Wii U Helper
Once you are done with above steps proceed to next page to Install The Legend of Zelda: Breath of the Wild in Cemu and Play.