Continuous download errors for many days without any known reason.

I am having the same issue, regardless of what browser I use and the images never download. I have an unlimited stock license with full creative cloud.  

Based on my research on microstock forums, many users with unlimited plans like mine are experiencing this situation. They believe this could be a dirty tactic to prevent users from downloading their images by providing vague, irrelevant notifications that mislead users.

What kind of image do you want to download and where are you located? It is important that your region is the same as the region of the credit card, when trying to download assets from stock, as not all assets are available to each region. Your credit card region tells the system, what kind of assets you can access. If you do not see the asset using that region, you can't licence it.