"Under capitalism, it doesn't go to the people who did the labour."

Automation is removing the human labour factor rapidly, so that no longer holds true. Karl Marx's writings never anticipated cybernetics, transhumanism and genetic engineering despite his followers believing he was some kind of infallible prophet.

The machines will build themselves, repair themselves and run themselves.

Even in the 19th century you didn't need to be a prophet to ponder what will happen when machinery finally becomes fully automated, and what the process of arriving to this state might look like.

Indeed this is the main question of Marx's work.

so wait after you remove the need for manual labor do you go dystopian capitalism where people have no jobs and grow poor, or you distribute "universal high income" and start doing communism with oligarch supreme leaders determining who gets what?