The cache is not at the listed coordinates. To find the cache, you must first complete adventure lab cache "Thorndon Park - A Step Back In Time" - https://labs.geocaching.com/goto/ThorndonPark
Once you have the bonus numbers, cache can be found at
S34 52.ABA E138 41.CDE
Public Domain photo courtesy of State Library of South Australia: https://collections.slsa.sa.gov.au/resource/B+1662