Never came across one which is not free. However they require you to register your onboard unit at times, not to deduct money from your cash card but to remotely open the barrier.
Most condos have provision for 1 carpark lot per unit, and usually not all occupiers have cars. Occupiers with additional cars have to pay a monthly fee to occupy more than 1 lot.
Carpark lots are shared, on a first come first serve basis.