I thought it runs in Linux operating system since its an opensource and also because of widely use by the communities I guess I was wrong,
Don't blindly trust everything you find on sketchy web articles. You actually were not wrong; most people run Bitcoin Core on Linux machines, although it also runs on Windows and macOS. The website is simply wrong.
The thing that Blockchain itself is not an operating system while the website refers it as OS is very funny. It already felt wrong when I read it as OS and since various thread that are published on the forum itself tells us how it algorithm that is creating nodes, adding the info in it, building it into a block, and repeating the process as we move.
If I am not wrong then it is simply a mathematical expression getting resolved using miners brain and once its resolved we get the confirmation. Everything runs through the miners OS, transacts/broadcasts through the wallets, and all of them runs on specific OS.
I mean that's the simplification, I know it could be layman - layman explanation.