I would imagine you look on their website to find information on their STR regulations. See if you meet the requirements and if so use their application form to apply @Lyn-and-John2
if approved, they give you a number you need to upload onto your listing.
I’m in Darwin NT and don’t have this requirement so unfortunately I can’t offer any advice. Suggest contacting Support arm of Airbnb for assistance. They are my first go to point for that kind of assistance. Thanks Kate