Most of the time, when there is a download issue it comes from a momentarily unstable connection. For example, if your connection drops for a second it is very likely to kill the download.
No worries though, after each purchase we send you an email featuring an access to your purchase history from which you can download anytime. So you can connect there and attempt the download again.
If it still does not work out after a few attempts, please reach out to us and we will help you out.