Clone the repository and build the source:
git clone https://github.com/jpmorganchase/quorum.git
cd quorum
make all
make test
Binaries are placed within ./build/bin, most notably geth and bootnode. Either add this directory to your $PATH or copy those two bins into your PATH:
# assumes that /usr/local/bin is in your PATH
cp ./build/bin/geth ./build/bin/bootnode /usr/local/bin/