I don't know how Postmate operates. If they give you a W-2, you are an employee, not an independent contractor. If they give you a 1099-MISC they are treating you as an independent contractor.
If you are an independent contractor, you are the business. TurboTax is asking for information about you and your individual operation. It's not asking about Postmate. You own your own business. It gives you the option to use your own name as the business name, which is what you should do. Your business address is the same as your home address.
