The author's page links to the original SCP Wiki page, where you can read it in parts, as it was being created. It's not a straight book download, but you can think of each red link as a chapter.
Which link? Because the one I posted works, and it says:
> Suggested reading order is from top to bottom. For those wishing to read the book There Is No Antimemetics Division, begin with "SCP-055" and finish with "Champions of Nothing."
Checked every one of those links, which also work. I can't understand why are you... wait, what were we talking about?
Beware: SCP is as enthralling as TV Tropes.
https://scp-wiki.wikidot.com/antimemetics-division-hub