OK so probably one in ~Darwin (because gateway hub for Pine Gap), one in ~Canberra (because capital) and one in ~Adelaide (because center of the industry).
Haha. I'm sure any intel agency worth its salt can do better than my supposition. Sleeping on it, I realised that since Singapore is presumably a major five eyes sigint hub there is likely an additional attraction to Darwin re. reduced latency access and reduced transit costs for newly captured undersea cable data from Asia.
RTT estimation will triangulate the minimum path delay and I hazard other info like flight exclusions and truck gps manifests will identify the locations. Nothing about datacenter locations stays secret long. (Obviously there are ways RTT can be fooled, misled or be inaccurate)
The location is not top secret. It is certified to host top secret data and applications (there are numerous regulations... so many that you'll want to self terminate...)
Not sure if this question is a troll but in the off chance it isn't here is a sample budget for the Australian government https://www.aph.gov.au/About_Parliament/Parliamentary_Depart.... It looks like the average revenue for a given year hovers a little under half a trillion dollars. So yeah they can afford it. The idea that "their coffers are empty and their balance sheet is negative" also indicates serious ignorance about how governments finance operations. I'd suggest you start with the country you currently live in and understand how your own government finances its operations. That will likely help you understand how Australia does it.
You are trolling. Australian Government revenue was AU$755.8 billion in 2023, net assets of AU$790 billion and a budget surplus of AU$18 billion in 2023/24.