Not sure if it has changed but when I did my you got an ARN and then to complete the training just had to apply for either an ASIC or AVID, you were not required to hold one to undertake training just to have applied and be accompanied by an ASIC holder when airside. You require a CASA licence for an AVID but not for an ASIC. It is a long and bizarre process, it took me 12 months to get a CoV issued to allow me to fly the IREX test due to CASA constantly coming back with more request for information, got there in the end though.