After that time, you can apply to the District Court to have the order enforced. This is free. The cost of enforcement will be added to what the other side owes. But you will have to drive the system. At each step, you will have to contact the District Court and fill in the appropriate forms.
Nothing happens automatically.
The registrar decides how the debt should be paid. The registrar might decide the person should pay by instalments. Sometimes the registrar might decide the other party cannot afford to pay the debt. A distress warrant is an application to have a bailiff visit the other party to demand payment for the amount owing, and seize assets if they don't pay. A bailiff can only seize items that are owned by the other party.