Must there be an ambulance and a medical room at the ground?

Yes, both are the home club's responsibility under NSL Handbook Rule 14.11:

• Ambulance (14.11.9): throughout the match, a fully equipped, dedicated and appropriately insured ambulance, suitable for carrying an emergency casualty and staffed by someone qualified to give essential emergency care on the way, must be available at the ground to take anyone needing emergency treatment to hospital.
• Medical room (14.11.8): a medical treatment and examination room close to the teams' dressing rooms, with the mandatory facilities and equipment prescribed by the League.

The home club must also arrange medical personnel, equipment and facilities for the care of everyone at the ground, in line with the relevant legislation (14.11.4).