If the new car is not licensed, just print the frame number on the compulsory insurance document.

Some places need temporary permits, while others don't. This has no effect on the claim.

If you buy a car and have already bought insurance, the insurance company can pay for the accident. However, in order to reduce the risk, it is generally stipulated in the policy that the insurance liability for theft and rescue begins to be calculated from the date when the company obtains and corrects the license plate.

Further reading: How to buy insurance, which is good, and teach you how to avoid these "pits" of insurance.