EliteSpawner's source code isn't public yet, but we plan to open it up in the future. Once you have the code, this page walks you through building it.
Bought EliteSpawner? Ask for the source
If you own EliteSpawner, you can ask for a source download. Open a ticket on our Discord and verify your purchase. Shared source code is for your own use, as covered in our Terms.
The project doesn't ship a Gradle wrapper jar. Open it in IntelliJ IDEA, which brings its own Gradle, or create a wrapper once with a local Gradle install: