I have found the solution! :) when you download the file, it should bring you to a folder titled "BTS-all". Open it and then go down to where it says "To the Edge of the Sky" but with the file type listed as 'application'. When you try to open it, it will say to either extract, run, or cancel. You must EXTRACT the files because it's required for the game to work. Once it's done, it should bring you back to the folders where you will then click the "To the Edge of the Sky" APPLICATION. This should open the game :)
