If your property has its own address, you can connect to the NBN network following the usual steps without any issues.
However, if your property does not have its own address, or shares the address of the primary residence, there are a few more steps that you may need to take to get connected.
Extended the Connection from the Primary Residence
If the owner of the primary residence on your block of land is already connected to the nbn (or plans to connect to the nbn in the future), then you may be able to simply extend their connection to your granny flat.
A separate option is sharing the Wi-Fi connection of the owner, however, this will of course be dependent on your relationship with them and any terms you will need to agree upon.