In trying install Sims 3 ambitions for my sister and theres an error screen that keeps popping up?

-its on a mac desktop and it says " :bolded: To install the sims(tm)3 ambitions you must have the sims(TM)3 installed, :unbloded: Select a volume where the /TheSims 3.kocalized/TheSims3.app is already installed" i did it to the game folder to the game itself and to program files, help please? i use windows 7 not mac!In computer terms, volume used as a noun commonly refers to an entire harddrive or partition. Try selecting the one that the main game is installed on. Chances are it will be "Macintosh HD".
do you have sims 3? if you don't, then you need it to play sims 3 ambitions. otherwise I don't know