Um, surely they had a civilization in OTL....
I'm not the best for knowledge on the Aborigines but as far as I was aware they didn't even have huts, besides temporary "gunyah", which were only for a night or two. They lived as hunter-gatherers and wondered as nomads, never staying in one place.
I don't think they ever had any civilisation at all, but I'm not sure, you'd have to ask an expert in that area.
I'm not sure why exactly they never developed civilisation, but I always put it down to a small population in a large expanse of land with no rival powers or tribes.