Spring Boot Skeleton
Flowable Engage is based on Spring Boot 2.1 and therefore requires it as a base for any development environment.
The easiest way to setup a Flowable development project is to first generate a Spring Boot Project by using the Spring Initializr.
Choose the following options and hit "Generate Project" to get a Spring Boot skeleton for a Flowable development project:

You can now import the project into the IDE of your choice (like IntelliJ IDEA or Eclipse).