The idea of that set up is for dispensing at parties directly from the keg, as a less frat-party looking option like a cobra tap, though not as nice as a jockey box. So you first force carb the keg to desired volume co2 at home in your kegerator. Then bring keg and co2 to party. Install the gas line and ball lock faucet, pull the pressure relief valve, and set your pressure to 1-2psi, or just enough to push the liquid out. The dissolved co2 stays in solution for a while, depending on temperature and time. It's not a long-term option, unless you're willing to change your co2 pressure constantly.
Fermenting: Irish Stout, Ciderale!
Serving: Oktoberfest, Immodest Clone
Up next: Black IPA, Maple Porter