Do you have to get car insurance as soon as you get your license or can you just drive your parent's cars without an insurance of your own?

You need insurance if you own a car. As long as you are living with your parents and driving a car titled to them (even if it is "your" car), you just need to make sure you are listed on their policy as primary driver of your car and an occasional driver of the other family cars. They might save a dollar by having you EXCLUDED from the family car, but then you would have no coverage if you were to drive it.