This error occurs when the download link we emailed to you has expired or otherwise become out-of-date. This only happens very rarely, and we try very hard to minimize the instances where it does.
If you have an account, you can access your updated download links right now from your Downloads page. Don’t have an account yet? You can create one here. If you use the same email address as you used when previously checking out, you will find all of your old orders synced to your new account when you complete the sign-up process.
If your order is not appearing on your account, or you would prefer not to create one at all, then please contact us and we’ll fix it up as soon as we can. If you have it handy, please include your order number. Thank you sincerely for your patience.