When you first use the Wilson Parking App, you will be asked to "Join for free". Here you can set up you account, where you can then make an online booking, sign up for a monthly subscription or Pay by App all from your phone.
You will need an account to make your first booking. If you have not set up an account, click on Book now from a car park page, and you will be promptd to set up an account.
Want to use the website to set up your account? Go to https://www.wilsonparking.com.au/book-online/ to get started.