You misunderstand.

The repo you're referring to is Railwaycat's mirror of Yamamoto Mitsuharu's codebase. (which previously was only available via ftp and tarballs.)

Yamamoto has recently migrated to git and hosts a repo at Chiba U, the address is: http://www.math.s.chiba-u.ac.jp/~mituharu/emacs-mac.git

HOWEVER. Railwaycat does still maintain the Homebrew tap and formula for installing Emacs Mac Port

Here: https://github.com/railwaycat/homebrew-emacsmacport

A simple install via:

   brew tap railwaycat/emacsmacport
   brew update
   brew install emacs-mac

And you have a far superior Emacs for OSX than that built by emacsformacosx.com.

Once built, you can (without any problems) move the Emacs.app into your /Applications/ folder.

Don't do yourself a disservice, install Emacs Mac Port now.