Hi Eric,
Thanks for using my plugin. You plosted some great questions there. I have the answers to them.
- Yes. You can grant access only to registered users by specifying the access level of the article that the plugin is being used in, or you can set the access level for the plugin itself, in the plugin manager. A quick look in your plugin manager, or article manager will reveal the access level setting. If you can't find it, let me know, and I will post a quick how-to.
- Unfortunately, there is no way to turn off the empty folder message. Maybe, I can update it in the next release to have that option, but as for right now, there is no option to do that. You might have to be creative in your message, since, at least, you can specify what message you want the user to see in an empty folder.
Hope this helps.