I forgot to say, the reason you should make a copy of the Original Game because when you mess with the game folder you cannot go back to original without deleting all the common files and re-downloading the game cause when you mess with the file you can't put another mod into it cause it usually doesnt mess with all of the files of the last mod so some assets will stay in the game and it'll mess up the game and make it not work.
I forgot to say, the reason you should make a copy of the Original Game because when you mess with the game folder you cannot go back to original without deleting all the common files and re-downloading the game cause when you mess with the file you can't put another mod into it cause it usually doesnt mess with all of the files of the last mod so some assets will stay in the game and it'll mess up the game and make it not work.
MMK