I'd like to make three suggestions:
1- In Configuration -> Notification Email ->Email Notification Editor, please verify if Sender Name and Server email fields are blank when "Save" button is pressed and launch an alert if true in order to avoid messages like: "Sorry, you do not have permission to access this page."
2- It would be fantastic to avoid subscribers to edit the name of a category, but let them to upload files inside it.
3- And last but not least, it would be good too, in the same way as in the moderation of comments, to add your plugin the possibility of reviewing by the administrator the content of the files uploaded before making them public. In our case, we need that possibility because we want users to share files with each other, and this could be very dangerous.