Infrastructure Partnerships Australia interview questions

Had a first round interview over the phone that went well. Then did a one-on-one in-person interview that also went well. I asked about a salary range but was told they didn't know yet. The interviewee seemed like he didn't appreciate me asking about it. Got invited to a third interview, where I had to complete a task prior to the interview and then in person I would meet with a few people from the company to discuss the task/other interview questions. Did this and everyone was very positive, kept saying how great my experience was, my research task was very good and that I would do well in the role. Once again I asked for a salary and they said I had to nominate a salary and it would need to be approved by the boss. There was also supposed to be at least one more interview round. Time passed and I asked about the next round, stating that it was fine if I didn't make the cut, but I just need to know because I'm interviewing for other roles. They told me it would take a long time to decide and get through the rest of the candidates, but they would definitely get back to me. More time passed and I received another email saying that they would get back to me. Of course this never happened, which was fine because by the second time they contacted me I had almost forgotten about all of this. But when this was all happening I really did wonder if it was a scam because I am always sceptical of being asked to perform a task that takes many hours of preparation, plus they were very cagey about salary and couldn't even give me a range when asked, they kept asking me to nominate a number. I've also seen the role being advertised repeatedly, suggesting to me that this may not be a real role, but instead some way for the company to collect people's information. Not sure but overall I wouldn't recommend interviewing for this company.