@Balthanon - FanFicFare has a feature "Get Story URLs from Web Page" that you can use to get lists of URLs from author pages or favorite pages.
For ffnet specifically however, it's a little more complicated. Because they use javascript on the author page to switch between author's stories vs author's favorites, you have to use the mobile URLs instead. Change the www to m. Examples:
https://m.fanfiction.net/u/00000/Author-Name
https://m.fanfiction.net/u/00000/Author-Name?a=fs
Because your own followed/alert list is behind a login block, FanFicFare can't read it. (FanFicFare doesn't login to ffnet because a) it doesn't need to to download stories and b) captcha.)
However, you should also be aware that ffnet in particular has a history of blocking users who download 'too many' stories at a time. What exactly is 'too many' isn't known. There's an
FAQ about it.
For long term, I recommend using
email notices to update your library.