Trouble Tales of monkey island chapter 5 mac

Legebrind

I've downloaded the game from steam and I cant run it, it says download starting but, I have downloaded the game. I tried to Defragment the game but it says use your system defragmentation tool, but i have a mac and i dont know if its posible to defragment without using steam. If some one knows what showld I do please answer ! Thanks! (sorry for my English I'm not a regular english speaker haha)