https://www.youtube.com/watch?v=sKwfejUfhlo
In this video it will teach you how you can install and run ragnarok offline server using the rathena emulator. Make sure to download and install the prerequisites first.
~~ Prerequisites ~~
► Visual Studio Express 2017
► MSysGit
► TortoiseGit
► Wamp Server
► rAthena Github