@waltraud, I think the one you are referring to is https://naturemapr.org/sightings/4560954, which is a bit further west. (Found record in species search on CNM, but had to go to the list which gives your name) and on species search of ALA (which gives a map). Ficus carica is on the ACT list of invasive alien plants (which relies on sightings) but not on ACT Plant Census (which relies on Herbarium accessions).
The specimen is certainly not a native of the area, and yes Max, there was a fig tree - the edible mediterranean Ficus carica - where we removed Cleavers, Black Nightshade, tomatoes (!) etc under Exocarpos trees. I took photos and recorded on CNM however since the mapping tool is removed from CNM, it would take me long time to find it again. I observed Fig trees (Ficus carica) in the Majura pines close to the border with nature reserve at the ridge and I think fruits are spread by birds, most likely Currawongs. The Census of Vascular Plants of the ACT doesn't list Figs, native or exotic... Obviously the specimen you recorded was tackled before but has re-sprouted.
Some of the leaves near the ground surface in the bottom of these two photographs, have their under-surfaces facing upwards to the camera, showing the glaucous (white or grey bloom on the leaves' laminas' surfaces), confirming this species identification.