Hello Peter,
In your _Imports.razor file (root directory) you are missing @using Syncfusion.EJ2.Blazor.
@using System.Net.Http
@using Microsoft.AspNetCore.Authorization
@using Microsoft.AspNetCore.Components.Forms
@using Microsoft.AspNetCore.Components.Routing
@using Microsoft.JSInterop
@using SyncfusionTest
@using SyncfusionTest.Shared
@using Syncfusion.EJ2.Blazor
Then in your /Pages/_Host.cshtml file you are missing the CSS and JS references.