Thanks for the reply! I think it's a Flaresolverr issue, I switched to running the Python file and it works.
Also, I think there's a bug in downloading long series from AO3.
For example, when I download "Get story URLs from web page" the series
https://archiveofourown.org/series/1344409 , the series numbers don't match with those found on AO3.
For example, 2 stories are downloaded with [74] in the series, and no [73]. Also, the series number that gets downloaded doesnt match with the one on Ao3. For example, [64] that gets downloaded by Fanficfare ends up being "Hangover", but in AO3, it's supposed to be number 65. And Fanficfare doesn't download 65 at all.
It also downloads 2 different stories and labels them as 67. One of those downloaded as 67 is listed as 68 on AO3, "A pint of bitter and a cider".
These are just some of the examples.