Here is what the folder structure should look like for game loading:
💾SD/USB:
┣ 📂wbfs
┃ ┣ 📂GameName [gameID]
┃ ┃ ┗ 📜gameid.wbfs
┃ ┗ 📂GameName [gameID] --This example is for split wbfs files, if you are on ntfs or your game is smaller than 4gb, ignore it
┃ ┣ 📜gameid.wbfs
┃ ┗ 📜gameid.wbf1
┗ 📂games
┣ 📂GameName [gameID]
┃ ┗ 📜game.iso --note: this is LITERALLY game.iso, not the name of the game, or the game id, just game
┗ 📂GameName [gameID] --This example is for multi disc games
┣ 📜game.iso
┗ 📜disc2.iso
Note: the WBFS folder is for WII GAMES ONLY and the Games folder is for GAMECUBE GAMES ONLY
get the game IDs here: https://www.gametdb.com/
For Wii games you can just use any of the programs found on this page as an easier alternative to manually creating the folder structure: https://wii.guide/wiibackupmanager