The advert uses Powerball pictures but the terms sound like a bet paid by the company. That may be a totally different product from owning a US ticket. What should an Australian player look for in the licence and terms before comparing anything?
Start with the product and the licence. A physical-ticket service says who purchases and holds an issued ticket and how a claim works. A lottery wager pays under the operator's own terms without giving the customer a US-issued ticket. Australia prohibits online betting on the outcome of a lottery, and an online wagering service offered to Australians must appear on the ACMA register where licensing is required.
Do not rely on US lottery logos or the phrase same jackpot. Check the operator on ACMA's licensed-provider register and read the ticket-or-wager terms before depositing. Mega Millions also says its tickets are not sold outside the US and does not endorse companies claiming to sell them internationally.