Not really. An Archipelago is a chain or cluster of islands - not merely any landmass, however large, which has some offshore islands. If you used that latter definition, then you would have to count Australia as an archipelago as well. But if you accept Australia as an island, then why not Afro-Eurasia as well? It is definitely bigger.
The archipelago part was my mistake, but Antarctica is a continent either way, and that is why Afroeurasia is not an island either. They are Continental landmasses. Technically all land on Earth is islands but that is not how almost anybody views it as. I view Oceania as a continent. Australia as a country. Mainland Australia as an island.
Why is Australia an island, but not Antarctica? The difference in size between mainland Antarctica and mainland Australia is only 1.6:1. Between mainland Australia and Greenland, the world's biggest island, the difference is 3.5:1, the biggest difference in size between any landmasses in ranked order. There is no logical reason to draw the border between continental landmasses and islands between two landmasses with so small difference in size as between Antarctica and Australia.
With so small difference in size, either are both Australian mainland and Antarctic mainland islands, or both are continental landmasses. Anything other is meaningless.
Convention on this website is that Australia is not an island. Check any other island quiz and you'll see that this is the case. You're preference doesn't matter: it's misleading to the site's users.