Flowcharting requires Grafana v5+ to run (not tested with lower version)
Go to https://github.com/algenty/flowcharting-repository/tree/master/archives and download the lastest zip file.
$ cd $grafana_home/data/plugin
$ unzip <file>
Go to https://grafana.com/plugins/agenty-flowcharting-panel and click on "install Plugin".
grafana-cli plugins install agenty-flowcharting-panel