I'm not the person you responded to, but the Assistance and Access Act 2018 is probably a good place to start. Here is a page from the Aus Government about it, but the very short version is that the government can ask tech providers to assist them with building capabilities into their systems to allow the government to access data to help with the investigation of certain crimes. In some cases these will be voluntary requests, in other cases they will be requests that must be fulfilled, including asking providers to add capabilities that the government has developed.

There's a lot more detail about it, and the government insists that they won't ask providers to create systematic weaknesses or to decrypt communications entirely, but it's not clear to me exactly how those ideas are actually implemented. Unfortunately, much of the process (likely the entire process) is not made public, so as far as I'm aware there aren't any good examples of requests that the government has made and what sorts of things have or haven't been implemented.