We are agnostic about the tools you use, but here are some tips on getting started with common tools:
After checking out the project, on the command line, run:
> ./gradlew eclipse
This will generate the Eclipse project files for you.
You should now be able to open up the project in Eclipse.
Please make sure you install and use the EditorConfig plugin.
When you open the project in IntelliJ IDEA, it should detect that there is an unlinked Gradle project. Click on the option to Import Gradle project.
Make sure you enable the Use auto-import setting.
All the other IDEA config files are already configured so that everyone should be able to start with the same baseline.
If IDEA asks you about using EditorConfig, just say no. IDEA has better code style support and should already be configured to use the project default.