There are several places. Project Gutenberg has a large collection of e - books that are in the public domain, and many of them have been turned into audiobooks by volunteers and are available for free. Also, some local libraries offer free audiobook borrowing services through apps like OverDrive, where you can get a good selection of stories in audiobook form.
One great source for free audiobook stories is YouTube. Many channels upload classic stories in audiobook format for free. Additionally, Spotify also has some free audiobook stories, although the selection might not be as extensive as on dedicated audiobook platforms. Some podcasts also feature narrators reading out stories, which can be a form of free audiobook stories as well.