Add authentication middleware in application's pipeline

Startup.cs

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    if (env.IsDevelopment())
    {
        app.UseDeveloperExceptionPage();
    }

    app.UseRouting();
    
    // Below line adds the authentication middleware in our app's pipeline
    app.UseAuthentication();

    app.UseEndpoints(endpoints =>
    {
        endpoints.MapControllers();
    });
}