The KLM/QF code share does not really work easy. Every time I have gone to CBR in the past couple of years I have had to book my flights on klm.com to go to SYD/MEL/BNE and then book a separate domestic flight to CBR. The KLM site does not know of Canberra, or of many domestic flights. Despite them saying differently.

I have had lounge access once with my platinum status, but that was because the Qantas lady in SYD was being nice to me; this was basically Feb 28 2020, so right as covid was starting.