The Smart Store app is a Vue.js sample application, demonstrating the usage of the UI5 Web Components. You can find a step by step tutorial below on how to build the app by yourself. You don't have to clone the repo, the app will be built from scratch.
For the step#1, Shell bar should be in "@ui5/webcomponents-fiori/dist/ShellBar" instead of "@ui5/webcomponents/dist/ShellBar";