Upon further reading, it seems this is largely due to the fact that previous implementations of communist society have included an authoritarian government.
I'm mainly reading the Wikipedia pages but it seems that communism in theory is actually stateless and doesn't have a government at all, let alone an authoritarian one:
"A communist society is characterized by common ownership of the means of production with free access to the articles of consumption and is classless and stateless, implying the end of the exploitation of labor."
"Marx and Engels maintained that a communist society would have no need for the state as it exists in contemporary capitalist society. The capitalist state mainly exists to enforce hierarchical economic relations, to enforce the exclusive control of property, and to regulate capitalistic economic activities—all of which would be non-applicable to a communist system."
