When I tried downloading the files I just get this:

I tried several times and one time I just got stuck in an endless Cloudflare captcha loop. I also tried on an older version of Firefox, same issue. And after all those tries they apparently flagged me as a bot because now I don’t even get to see the page with the Abstract anymore, it just goes straight to the error page. Why do they make it so hard to download 12 PDF files? I hate the modern web…

Spotted Mars.