If I buy the iPad/iPhone version can I download for free on my Mac?

If you’d like to run the app on your iPad/iPhone and Mac, separate purchases are necessary. The reason for this is that each app runs on a different operating system — iPad/iPhone on iOS and Mac on OSX. Because of this, apps for each platform have to be developed from the ground up and are sold separately through their respective stores i.e. App Store and Mac App Store.