Wont download- says Error occurred on purchased page

I just purchased the game and when i clicked install, it went into the launchpad and never started to download. I clicked on the installation wizard and it said installation files are corrupted and to please download again. Im not good with computers so if anyone has had this problem and knows how to fix it please write how to in a review. Dont really wanna waste $25

rome total peace about Rome: Total War - Gold Edition