Antifa is not one organization, that's ridiculous. It would be like claiming that "Anarchists" are a terrorist organization.
Antifa is a decentralized organization: shared branding, shared tactics (borrowed from neo-nazis), chapters/affinity groups, mutual aid and coordination across cities.
Anarchism is a philosophy. Antifa is an actual terrorist network.
Feel free to send the White House a letter complaining. I did not write the big "ORGANIZATION" in the title of that EO. Or is it just bike shedding?