Fair question, but the point of the papers was to support a constitution that created a strong, federalized/centralized government, thus “Federalist”. Those opposed to the idea were against a strong centralized government, thus “Anti-Federalist”. So the titling is quite correct. The Articles of Confederation utterly failed so the continuation would have amounted to dissolution of the bands of our newly fledged country, with no unifying government to keep them from fighting. And fight they would.
Indeed, however there is more than subtle difference between “federal” and “national”.
Federalism has gone by the wayside in favor of much more “nationalism” in terms of how the US govt operates. Sovereign states chose to give up some of the principles of sovereignty for some nationalistic union benefits (which has now become the leviathan that holds states at bay or heel by fiscal distributive policy and law) .
Thanks.