Folder path is part of the URL for your presentation. Do the following steps to set your folder path:
Choose a library name, e.g. 'Folder 2'
Do you want to place this library under your user page? The answer must be YES for a Wikipedia website. The answer can be NO for Wikibooks, Wikiversity and other wiki websites.
If YES, folder path should be "/wiki/User:Yourusername/Folder 2/" or "/wiki/User:Yourusername/My Notebooks/".
If NO, use "/wiki/Folder 2/" or "/wiki/My Notebooks/".