I have created a menu item type List My Downloads with a Title Resources and alias resources. Also of course I set up a registered user and set that user as the creator of a couple of Downloads that were Registered Access.This has a link like https://www.mysite.com/resources
Then I logged on - the menu item and the separate direct link on its own page - both worked.Next I logged the user out and cleared all the browser cache. The result was an error message, see pic attached. As you will see it has the error message "0 - Using $this when not in object context" but also has the problem identified as possibly being "you have no access to this page"
So the user needs to be logged in before accessing that resource! To double check I set the permissions to Download as allowed and view access to Public. And it still failed.
Then of course I realised that Joomla!/jD had no user so it could not find and gave an error message. Sometimes a user may log out but the cache is still intact and maybe previously Joomla! 'remembered' the previous logged in front end user.