Adelaide is dead. Your best bet is to try and contact the Adelaide branch of the Cave Clan, assuming that you're over 18. While they are mostly into drains it will at least help you meet some fellow explorers in your area. I think there is a few Adelaide CC members.
Otherwise just go and check out those mainstream abandos you mentioned, get some flicks, share them around, get known and go from there.
Try instagram, while it may not sound like the best place, I have met a number of good exploring people from there. It's not all 15 year olds who think that breaking into trains is urbex.
Wander often. Wonder always.