Could someone explain to me the core lichess architecture as shown in this image?

[M-U-X]

in this imgae, ignoring all the none core parts, so any social aspects of lichess, analysis, and so on, what are the main/core components responsible for account management, match making, ongoing matches processing and sending data/moves, and storage of said matches and so on, and how are they deployed (number of instances scalability and so on)

I'm asking because I'm coding a similar project "just a similar board game" as a uni project, and wanted to model it similar to lichess, but I've not versed in scala, or many of the programming languages/Technolgies lichees is written in, any explaining would be highly appreciated