There is no need to start the ATOM, and you may disable the Windows Service.
Groovy 2.4.13 SDK
Boomi Integration uses Groovy v2.4.13 to run Groovy scripts. I recommend using this version 13 because you will want to test and debug your scripts with the same run-time that the Atom uses. (Groovy v1.5 is not supportet!)
I prefer using: %UserProfile%\.groovy\sdk\groovy-2.4.13
Using a Terminal Window
md %UserProfile%\.groovy\sdk
Note
There are newer version of Groovy Script, there are other 2.x versions and there are older versions, like v1.5. Do not download or install any of them! Boomi Integration uses Groovy Script v2.4.13 and that is the only version we want!
JetBrains IntelliJ IDEA - Groovy IDE
ScriptEase uses JetBrains IntelliJ IDEA. While I recommend using the Ultimate Edition for professional use, the Community Edition is good enough to get started.
You must scroll down a bit on the download page to find the Community Edition -> 650MB: