The cache is not at the listed coordinates. It is a bonus cache for the Adventure Lab "Canberra AM".
This Aventure Lab can be found in the Adventure Lab app (IOS or Android). If you can't find it then the link is:
https://labs.geocaching.com/goto/CanberraAM
Use the hints from each stage of the Adventure Lab and calculate GZ using the following:
S 35 13.ACB E149 07.ADE
Please replace as found.
For those interested, the listed coordinates (and background image) are of the location of the old 2CA tower. It was built in 1938 when the station moved from "Radio Hill". 2CA moved out in the mid 1970's and the site was then used by the community station 2XX until about 2000. The site is no longer active and most of the equipment and buildings have been removed. It is the only non-guyed AM antenna in the area.