It looks like step 4 here is a little bit buggy. https://www.bryntum.com/docs/grid/guide/Grid/quick-start/vue-3. The text in the "broad steps" section at the top doesn't match the text in the "Contents" section on the right for Step 4. Also clicking the "Configuring the Grid Component" link doesn't do anything. Additionally for Step 4, it looks like the same code snippet is shown under "Edit the src/App.vue file and replace the content with the following" and under "Create a src/AppConfig.js file with the following content:"
Thanks!