In theory, you’re right. In theory, practice matches theory; in practice, it doesn’t.

Is there a functioning communist state, anywhere in the world, that isn’t also an authoritarian state, or effectively a dictatorship? Has there ever been one?

The only functioning communist communities I’m aware of were the communes in California, nearly all of which have died out, collapsed, or otherwise fallen apart. I think there are still a few surviving ones, but community populations have always numbered in the dozens, and usually fewer.