
Find the fic you want and download it as a pdf, convert that pdf to an epub file (there’s converters online you can find) and go to the “send to kindle” page on Amazon, select the file(s) you want to send and send them, then on your kindle hit “sync” and they will show up under “documents”
I had the files as pdfs already on my computer, and some of them are no longer on ao3, so I just converted them. For the ones that weren’t removed, I just didn’t feel like hunting them down to redownload them when it was just easier to dump them into a converter. But it’s good to know that the converting step can be fully skipped