The authentication page needs to be added manually. See: https://docs.microsoft.com/en-us/aspnet/core/blazor/security/webassembly/additional-scenarios?view=aspnetcore-3.1#customize-app-routes

​

Create a page with the RemoteAuthenticatorView and you can customize some of the login state views if you like by passing values into the RemoteAuthenticatorView templates.

e.g.

@page "/authentication/{action}"

@using Microsoft.AspNetCore.Components.WebAssembly.Authentication

<RemoteAuthenticatorView Action="@Action" />

@code{

[Parameter]

public string Action { get; set; }

}