All modules
Modules 0 to 8 run in order and build one project. From module 9 onwards you can skip to whichever problem you actually have, as long as you have done the modules listed as prerequisites below.
Assume every module is for you unless it is badged otherwise. Two of the nineteen are single-track — Connectors, which is about the desktop app's own interface, and MCP, which does the same job by hand from the terminal — and those carry a badge. Everything else either has a track switch at the top or is one page that applies to both, which the page tells you when you open it.