Install Graphviz using Homebrew:
brew install graphviz
Why do I need this? This library uses PlantUML, which uses Graphviz a Python library which in turn uses dot, a native library.
Create a unit test (or something else that runs during your build), build the C4 model of your application using the Kotlin DSL and simply render it. See src/test/kotlin/nl/reinkrul/tools/c4plantuml/Example.kt for an example.