I know this will sound patronising, but have you read Engels ‘Socialism: Scientific and Utopian’ and Lenin’s ‘State and Revolution’. If not, these would basically answer your implicit question as to why we can’t just wish a perfect society into existence.
“Authoritarian”, like so many other liberal concepts, is an idea that - while not completely without reality - is designed to obfuscate how power really operates. For example, non-authoritarian states have freedom of the press. But that press is owned by and will only give the point of view of the Bourgeoisie. The point of Communism is to put power into the hands of the proletariat rather than the parasitic Bourgeois.
High rises in the sense of skyscrapers are never necessary or useful, because they have enormous upkeep costs which mean they will never really be affordable. I think medium density housing as is common in Europe, with communal yards, nearby parks and situated along public transport lines, is the ideal for cities, although these rowhouses do look beautiful - we don’t really have them in my country for some reason.