[Vuejs]-How do I implement Vue Router while using Vue UI?

Your codes in between lines 10-13 are must be as below, you called with components key, it should be component

const routes = [
  { path: "/", component: Start },
  { path: "/clubs", component: Clubs }
];

And you should change routes with router in line 21

const app = new Vue({
  el: "#app",
  router, // not 'routes'
  render: h => h(App)
});