Why do I get an error when clicking on a PDF download link in the membership?

Getting an error like the one in the image below?

If you look at the error, it says the request has expired. Basically, when you load a page in the membership, it creates an expiring link. If you return after a few minutes to that same page without refreshing it and click on the same link, you'll get an error. You just need to refresh the page to have a new link created.