You can't complete CTP Connect without it.
If you don't know the registration number (license plate), you might be able to get it from police. Look at your police report, or contact the Police Assistance Line on 131 444.
You need to take all reasonable steps to find the registration number, but if you can't you can still make a claim. Call CTP Assist on 1300 656 919 for more information.
If you believe that you are at fault, you can still make a claim. You will need to provide the registration number of the vehicle you were driving.