Many things to write about this film, many things to reflect, and many things to give context to. So just couple of stuff, my opinion, observations, and kind of a trivia.

1. Was asked, if it's an anti-communist propaganda.
Hard question to reply. And this will be a long musing.
It was made by communists. In 1969 if you weren't communist, you couldn't get a camera (state property) in your hand, couldn't get financial support (from the state) for a project like a film. But it was different times than the '50s, the failed revolution of 1956 made sure of that. And the events that transpired in the early '50s alienated the whole society - communists too - against the closed clique of leadership, they gave enough to get criticized by the posterity.
The hero of the film, Pelikán the dikekeeper, sometimes used to voice the creators' thoughts about communism and the evil that was done (intentionally or by mistake), they don't just show, they tell via him. Good example when Pelikán had the conversation with the bishop in jail. The bishop says, that the Church stood for 2000 years, and the Hungarian kingdom for 1000. They'll endure more, and he implies the communism will fall soon. Then Pelikán replies noone can start out 1000 years old. Somewhere everything has to start, and mistakes from learning the trade happens. It's the creators way of saying that the fault isn't in the system, it was just so new it had to come over its childhood illnesses.
The choice of the hero too supports that it was made by communists for communists. The audience usually supposed to identify themselves with the heroes of the stories. And this story presents a communist to them, with impeccable past (from a poor worker family, hid communists during the Horthy era) who might be simple, and not as knowledgeable ideologically, might not understand everything from the ideology, but believes in the cause, believes it's for the greater good, believes that the comrades upstairs know what they do, trustworthy, and can follow orders (to some extent...). And in 1969 the intended audience was communist and the hero is a person they would willingly associate with, an easy alter ego for them.
No, it really isn't anti-communist, even tho the criticism is directed towards it.