Some things don't work due to ongoing development.
You'll need a JDK... You can get one here: Oracle JDK's. Windows is [x86 (32 bit) and, x64 (64 bit, but mostly everything is 64 bit now)], anything else, you should know what to do or who to contact. Anything newer than version 17 should work. I compile to version 17, but you can change that. Minimum version is Java 9 for Process.pid() and, if I recall correctly, there were some Bouncy Castle cryptography changes requiring source version 11.
You'll probably want an IDE. I'm working on an editor, but it's slow and careful work. I use NetBeans 18 (Install JDK BEFORE NetBeans) and a Java Ant Project with Existing Classes and package to .jar using ca.tecreations.apps.deploy.Deploy, but you can use any text editor and Command Promt, or terminal, or jethro.jar to launch. Compiling is automatic, according to configuration, via JavaCompiler.
You can construct a Maven/Ant style project by using DependencyViewer.
java -jar jethro.jar
command.