In order to install the current build (1.1 Alpha Build 2 + Hotfix 1) you have to download and install the base Alpha Build 2 package (JEBMMP 1.1-a2.zip), then download and apply the Hotfix 1 afterwards on top of it (JEBMMP 1.1-a2h1.zip). Further installation instructions will be in the Readme located in the EB\documentation\JEBMMP\ folder of both packages. Make sure to read them both.
Before you install: Remember to check the Readme of the build you’re installing, as there is important information that you need to know before you can install the Mega Mod Pack. The Readme (and Changelog) can be found in the EB\documentation\JEBMMP\ folder