Funny you ask, I actually made an entire Marxist-Leninist introductory reading list! It's designed to introduce key concepts and take you from no knowledge of political theory whatsoever into becoming a good cadre in any ML org. You obviously don't need the whole thing, though, you can just read or listen to section 0a and you'll be more than good, even just the first half of the section.

Communism, essentially, is economically compelled by the existing trends of capitalism, ie centralization of markets around a few firms and sprawling production and supply chains, as well as capitalism's contradictions, like overproduction leading to crisis and the struggle between workers and owners (workers want more for their labor, owners want to pay them less). Collectivized production and distribution has a number of ways to account for labor and resource management, it's far more complex than just getting everything for free.

Let me know if you have any questions!