My instinct is to treat 'Annie's Archive' like a repository first and an author second: there may be many contributors. Practically speaking, if you want to know who wrote a specific ebook from that archive, open the file and look at the title page and copyright page — that's where the credited author name lives. The bio for that credited author is most commonly located inside the same ebook (search for \"About the Author\" or \"Biography\") or linked from the ebook's landing page on the archive site.
If the name on the ebook is the archive's curator (Annie), then her bio is usually on the main website — check a sidebar, an \"About\" or \"Meet Annie\" page, or look for a profile link next to download buttons. If the site lacks that, try the Wayback Machine, the site's contact info, or any social media links the site owner left; sometimes the curator links to a short bio on Twitter, Tumblr, or a blog.