I know that this question was asked a while ago, but for any other users out there, here's what I did. (I am also on Mac OS X 10.9.5)
If you're sure that you downloaded all the necessary files, go to your system preferences, and then security and privacy. Click the lock at the bottom of the window to make changes and type in your administrator password. Above the lock symbol, there should be this sentence: Allow apps downloaded from... Below this there are three options; Mac app store, Mac app store and identified developers, and Anywhere. Click Anywhere, and if a message comes up, click allow. After that, close system preferences, and try opening the file again. It should work this time.
It worked for me, and if you figured it out, great! For anyone else having this issue, give this a shot.