if you want to use redmine-gantt, you should act follow command.
git clone https://github.com/katsugeneration/redmine-gantt.git
cd redmine-gantt
npm install
npm run build
before you use redmine-gantt, you make settings.json that written Redmine access information.
{
"name" : "Redmine login name",
"password" : "Redmine login Password",
"host" : "Redmine host name",
"protocol" : "access protocol (http or https)"
}finally, you run start command.
npm start
MIT