Any description of the origins of Antifa is woefully incomplete (I would argue intentionally so) without a description of what they were opposing. All other political parties, groups, etc eventually rolled over to the Nazis. The various Antifa groups (including the one you mention) bitterly and violently fought them to the end. This is what inspired what became the antifa movement of today. Also from your link (I wonder why this wasn't pasted and underlined in your post?): "The modern Antifa groups have no direct organisational connection to the historical Antifaschistische Aktion."
For the record, I'm not saying anything in America is like Nazi Germany and therefore I typically disagree with "antifa" tactics.
Link: https://en.wikipedia.org/wiki/Antifa_(Germany)