Tasmania has been an Australian state since 1901.
At first, I was confused about this "Australian island state of Tasmania". If Tasmania is an independent state(nation), why is it described by "Austrailian"? It seemed to imply it's a part of "Austrailia", which contradicts it's an independent nation, but implies it's a part(or a state like California in the US).
So I think "Austrailian" just means "within the boundary of Austrailia", doesn't it?
ex)Tasmanian devils are a marsupial now found only in the Australian island state of Tasmania. They mainly eat animals that have already died. They weigh up to 12kg, and they are between 50 and 80cm long. They resemble small black bears and have a bushy tail about half the length of their body. They
are surprisingly fast, and can climb trees and swim across rivers. The newborns are pink and lack fur. The young grow fast and come out of the pouch after around 100 days. They become independent after around nine months.
State and territory government - australia.gov.au
See the above link for info on the States and Territories of Australia. Each of them have certain devolved powers of government, but they are all very much part of the one nation.
I'm not a teacher of English, but I have spoken it for (almost) all of my life....