This client is a part of the YunoHost project, and can not be installed directly. Please visit the YunoHost website for [installation instructions](https://yunohost.org/install).
This command will install all dependencies and start a dev server (based on [webpack-dev-server](https://github.com/webpack/webpack-dev-server)) with Hot-Module-Replacement (live updates on code modification without reloading the page nor rebuilding the whole code). After the build step, click on the "Network:" link and you are good to go.
You can also install [Vue Devtools](https://addons.mozilla.org/fr/firefox/addon/vue-js-devtools/) (module for Firefox but also exists for Chromium/Chrome) if you want component trees, performance views and so on.