No state was fascist after the fall of Nazi Germany and Mussolini’s Italy. No way Croatia could’ve remained under NDH control after the war but Communist SFRJ wasn’t the only alternative. That alternative was forced by the Western Allies which switched their support fully to the Communists during WW2 and upon its conclusion. There were western democratic currents already in Croatia even before WW2 and those democratic organizations administered the Croatian democratic ‘banovina’ before Germany invaded. Some of the democrats were killed or exiled by the NDH government and the communists but not all of them were gone. The Western Allies had already made a deal with Stalin and part of that deal was Yugoslavia to the Soviets’ sphere of influence for Greece which would come under Western influence. This was a forced marriage like the first one dictated by the politics of more powerful nations. It’s like asking natives to thank colonial overloads for even existing.