Hi,
Thanks for the request for making these downloadable. At the moment, we have disabled this feature on purpose. We have plans to make the next iteration of the learning platform view-able offline. So that feature is coming. We recognize that having these assets view-able where ever you are is important and we are building that functionality in a way that maintains course integrity. You can expect this feature to appear in early 2019.
Thanks for using our learning materials and providing us feedback.