On Macs Cromwell can be installed with
brew install cromwell
Otherwise you can download the Cromwell Jar from the releases page.
Set up Google Cloud Tools for access to docker images:
First download and install the Google Cloud CLI: Quickstart: Install the Google Cloud CLI | Google Cloud CLI Documentation
Then authenticate with Google for access to the docker image registry
gcloud auth login gcloud
This is a companion discussion topic for the original entry at github.com/aryeelab/topology-tools/preprocess_rcmc