vue

"export 'App' was not found in './App.vue'

make sure you don't have { } around App at import. It should be like this:

import App from "./App.vue";

quickstart

https://ej2.syncfusion.com/vue/documentation/treegrid/getting-started/

npm install -g @vue/cli
npm install -g @vue/cli-init
vue init webpack-simple quickstart
cd quickstart
npm install
#...