The so-called “independent” Croatian state in WWII was a fascist, collaborationist regime that in no sense was independent. It was at all times under Axis occupation until near the end of the war, albeit with vigorous opposition from Tito’s partisans.
NDH was as independent as say Canada is from Washington
I suspect that like most Europeans, Croatians were terrified after the communist atrocities in Spain’s Civil War were known to the world, and the Western democracies did nothing to spare them the same horrors of communism. Anyone who opposed communism, especially closer to the USSR borders, would be welcomed with open arms. Hitler and Mussolini came to power when their legitimate governments saw them as defenses against communism.