How Do You Update The Voidlauncher

So I downloaded the VoidLauncher and to play a mod pack it says I need to update it so I downloaded the jdk but when I click on yes to update the launcher it still tells me that I need to download the jdk. Do I need to do something with the jdk to update the launcher? I am very confused as this is my first time using a mod pack and help would be greatly appreciated.

PS I am on a Mac OS running El Capitan