Greasy Fork is available in English.
Adds download buttons to each work blurb on AO3's works index pages.
< Opinie na ao3 download buttons
I don't think it is possible to do that in a single click, because AO3 doesn't offer multiple files zipped up into a single download. You would still need to click through the "Save file" dialog for each work.
Is there a way to add a Download All button? So I can download all stories on a specific page without having to click download for each story?