A: This means your game files are encrypted, and CEMU cannot find a matching key. Either obtain the key from your own console or re-rip the game in Loadiine format (which is partially decrypted).
: Today, many users prefer downloading games in decrypted formats (like .wua or the "Loadiine" folder format), which bypass the need for a keys.txt entirely because the files are already unlocked. Where to Find Them Today
Open the file named keys.txt with a text editor like Notepad.