Well, yeah I don't know anything about that particular keg, but generally speaking, when kegging, if you're getting just froth and flat beer, your beer is overcarbonated, your pouring pressure is too high, or your beer is too warm. I guess it's also possible that there is a partial blockage in your beer line which is causing turbulent flow.
That's not a keg! It's an oversized PET bottle with a car valve shoved on top...
Seriously, you didn't describe how you poured the beer, but there's a good chance that you didn't purge the air out of the tap or uptake line if it has one. Dropping the head pressure is a good start and see how a slow and steady pour goes. Keep the beer really cold to increase the uptake of CO2 in solution...