The soviet union was authoritarian state capitalist (as opposed to market-capitalist). It just called itself communist, even though the Soviets (worker's councils) were suborned to the party very rapidly.
They literally all copied the soviet union's homework (Marxist-Leninism), there are other theories that haven't had the chance to be tried. Like Council Communsim, Syndicalism, Libertarian Communism, Anarchism, etc. The failure of Marxist-Leninist countries proves Marxist-Leninism doesn't work. It doesn't prove that communism doesn't work