Before installing, make sure that you've already generated SSH keys on your machine and added them to your GitHub account.
You also need to install a CMSSW release. You can do this with the following:
cmsrel CMSSW_xx_yy_zz_patchp
Inside of the appropriate CMSSW_xx_yy_zz_patchp/src clone this repository.
Then,
cd Analyzers/FatjetAnalyzer/test
bash install.sh
At this point, you should be able to run the basic code. For more advanced functionality, refer to the applicable directions on the repository wiki.