Layover at Guangzhou

Hi, I am australian passport holder. I arrive from Kolkatta India to Guangzhou by plane (Indigo airlines). I have a flight to melbourne within 6hrs of my arrival. But i need to cross china immigration to collect my baggage and then do checkin for flight to Melbourne. I have confirmed flight. Do i need any visa? If yes, can i get it airport or do i need to apply?

Kindly respond asap.

Cheers
sumeet