To run with geoflow/geof download the whole repository (leave the directory structure intact) and run the runner.json flowchart.
By default runner.json should load the test data from the test-data folder. And when you run it should produce output in the obj and cityjson folders (they will be created).
NOTE. If you have not setup a postgres database you might want to remove the OGRWriter nodes (in the gui: shift+click and press delete)