This project is defunct. It has been renamed xmlcalabash3-scalal-archive and I expect it to be moribund for a while, then private for a while longer, then eventually deleted.
Sometimes things just don’t work out.
You probably want the https://github.com/xmlcalabash/xmlcalabash3 repository.
This repository contains what used to be the “3.x” version of XML Calabash implemented in Scala.