Hey,
If your dad’s receiving family tax benefit then you click yes for a different question and you have to upload a copy of a Centrelink statement and write on it that he’s your dad.
If you are receiving Centrelink yourself, but the money is just going into an account that’s not under your name (this is different to your parents receiving benefits for you) then you should just be able to use your number - if this is the case it’s probably best to either login online or call Centrelink to confirm that the benefits are actually in your name not your dads.
Most people don’t get Centrelink in their own name whilst in high school and living at home - I’m on my mums health care card and have the associates benefits but don’t have Centrelink money. So it’s likely the first case, definitely check if you think it’s the second though.