@Kemmkrr Hello! The game will always look in the Mods folder that exists in Documents / Electronic Arts / The Sims 4 folder. It is not possible to have CC stored anywhere else and have it show up in the game. However, it is possible to move The Sims 4 folder to your external hard drive and create a symbolic link in order for the game to recognize it there. Here is a link for how to do that. Please read the entire article carefully and pay close attention to the advice given in the introduction. First and foremost, make sure you have created a backup of your The Sims 4 folder before doing anything.
