Sorry to hear that! Are you playing the game in the browser, or are you using the downloaded Mac build? If you're using the downloaded build, make sure you unzip the game before running it.
If you've downloaded the standalone Mac version, you just need to double-click the .zip file and it will unzip the app file, which you can then double click to play. Were you using the downloaded version or the browser version when you got stuck with no characters?