The Sentient Machine is an interactive puzzle trail. Nothing is linear. You might unlock level 33 before finishing level 5, and that is okay. That is the spirit here.
A Node will light up in the hub when all stars are collected from it. Some nodes have multiple solutions, each giving stars depending on difficulty.
Although stars exist, I would say eggs are the main progression here. Eggs unlock new gigantic hidden levels, new sections in existing levels and more. hint for eggs: try EVERYTHING.
TSM will require external tools, mainly for steganography. I suggest https://daniellerch.me/stego/intro/tools-en/ and aperisolve.