Which implementation of Marxist economic setup was ever democratic? Marxism has been authoratian or dictotrial since its birth.
Unfortunately for humanity, Marxism has only taken hold in a few places that were rather primitive and had no traditions of freedom and democracy. Unsurprisingly, the powerful elites in Russia, China, and Cambodia took advantage of that and turned Marxism into the state religion. With all the usual problems of an authoritarian theocracy, like genocidal disasters.
Here in more democratic places we used socialism to improve things.
But the Communist authoritarians sold out Marx and his dream of "the withering away of the state" because humans tend to do that.
Tom