Assigning and kind of item (images, posts, folders, and custom posts) will not affect the URL of the item. The URL of the item will stay the same before and after you assign it to a folder.
To learn more about how to use the plug-in click here, and don’t forget to check our entire Folders knowledgebase to make the most out of it.
Click here to learn how to move an image to a folder and here to learn how to bulk organise media. Click here to learn how to move a page or post to a folder and here to learn how to bulk organise your pages and posts.