Whether you need a licence or not depends on what you intend to do with your drone. If you are flying for fun in a recreational or hobbyist activity you do not generally need a licence provided you follow the standard operating conditions determined by CASA. Remember, there might be some local council or national park rules you need to be aware of. You should research the area you are intending to fly to make sure you comply with all the requirements.
If you are flying a drone under 2kg commercially – for hire or reward – you need to notify CASA before you fly and follow the standard operating conditions. (https://www.casa.gov.au/standard-page/flying-drones-commercially)
If you want to fly a drone commercially that is greater than 2kg or outside the standard operating conditions, you will need to be licensed and/or certified to fly.
Your individual permission to fly is called a remote pilot licence (RePL). Even if you hold a RePL, you will need to hold or be employed by someone who holds a remotely piloted aircraft (RPA) operators certificate, or ReOC.
The Ripper Group Training Academy can provide you with the training required for a RePL and assist you with your ReOC.