Place it in Android/data/org.citra.citra_emu/files/sysdata . Libretro (RetroArch): Place it in ../saves/Citra/sysdata . Troubleshooting AES Key Issues
If you are still receiving errors, it is likely because your keys are outdated or incomplete.
Once you have your aes_keys.txt , place it in the folder of your Citra directory. If the folder doesn't exist, you'll need to create it manually.