On http://support.aerosoft.com you hit the "Sign up" button to register a new account with your email address and a freely chosen password. The account here is not linked to an account you might also have for the AS online shop.
Afterwards you hit the "Add product" button and enter the license key that came with your AS box product. You should repeat step with all of your AS box products.
You will see that all your products are getting listed and have an "Update" button next to them. Hitting that button will give you a download link to the latest available versions and updates.