You will need to register if your business exchanges digital currency with money, or money with digital currency. Digital currency is a digital representation of value which functions as a medium of exchange and is not issued under the authority of any government body.
By registering as a digital currency provider, you will be registered on the Digital Currency Exchange Register which is maintained by AUSTRAC. There are compliance obligations such as suspicious matter reporting, threshold transaction reporting, adopting an AML / CTF program that reflects your business risks, operations and record keeping.
It is an offence to provide digital currency exchange services while unregistered.