As Tonky already stated the client is written in Java and thus platform independent - as long your OS supports minmum Java 1.5 for default client (Webpage Play Button). !->
http://support.apple.com/kb/HT5648It's
your turn to check what OsX version you have and what Apple Java version you run or be able to run.
The Devs are the wrong adress when it comes to Apples weird Java politricks...
Ender custom client on Mac OsX - should be no problem with Apple versions of Java 6
viewtopic.php?f=27&t=32796&p=452146#p452146Java7 for OsX only 64 Bit, Maverick (10.9) uninstalls Java 6 you have to reinstall:
viewtopic.php?f=27&t=32796&start=130#p453445Check it out - when problems or questions post in that thread please