Weird. I've tested on a desktop and mobile device. Both loaded the archive.is link via Tor Browser (no extensions) without a problem in both "Normal" and "Safer" modes. "Safest" mode fails at the CAPTCHA page but that's expected.
Maybe the node(s) you were connected to were having issues with that domain at the time.
That makes sense. Not a misconfiguration on the site's end then. Thanks for the clarification.