As far as I am aware, there are not populations of Jerusalem crickets in Australia. Instead, you most likely captured an insect from the same superfamily of Stenopelmatoidea. Some king crickets are native to Australia. Anostostoma Australasia is native to south-eastern Queensland and north-eastern NSW. They look similar to the Jerusalem at a glance, though they have spiny legs and can typically be darker. They have huge jaws like the Jerusalem.
There are five species in the Anostostoma genus. All are endemic to Australia. There is a small (but unlikely) chance you found a weta, however, these insects are native to New Zealand. One may have found its way across to the mainland, but I would bet you have a king cricket of one of the Anostostoma species.