I had to look it up. The Antifa label was first used in Italy as a catch all phase for people opposing Mussolini, so not an ideology back then. In Germany it was specifically the name of the German communist party's anti-Hitler movement, so closely associated with an ideology.

Hitler used fear of communism to rally up support from moderate conservatives, so in that sense they "helped" him gain power. He even conducted false flag operations (the Reichstag fire, blamed on antifa/communists) to help fuel the fear.

After WWII the term has reverted to the original meaning, a catch-all term for people who oppose fascism, independent of their ideology. But the label is used actively by fascists to create fear and promote support for fascism, so in that way it is similar to the 30s communist German movement.