Starting a business on Instagram isn't as simple as making an account and posting. There's lots to consider, such as how to protect users' personal information in line with privacy laws, and what information you are legally required to disclose when advertising on Instagram.
If you're working with ambassadors, it's best to set out the details of your arrangement in a Brand Ambassador Agreement.
Further, you need to comply with the Australian Consumer Law, which is designed to protect consumers from unfair business practices. Put simply, you should not mislead or deceive online users about what your business provides.
It's best to chat to an expert lawyer who can advise you on the regulations that apply to you and guide you through your options.