首先，我们需要在ASP.NET Core应用程序中安装一个名为Microsoft.AspNetCore.Authentication.Cookies的NuGet包。此包将提供我们在应用程序中设置角色/策略以及登录重定向路径的功能。

接下来，我们需要在Startup.cs文件的ConfigureServices方法中，添加以下代码：

services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme)
    .AddCookie(options =>
    {
        options.LoginPath = "/Account/Login";
        options.AccessDeniedPath = "/Account/AccessDenied";
        options.Cookie.Name = "MyAuthCookie";
    });    

上述代码中，我们添加了身份验证中间件，其中options.LoginPath和options.AccessDeniedPath属性定义了登录重定向的路径和访问被拒绝的路径。我们还设置了options.Cookie.Name属性，用于设置Cookie的名称。

接下来，我们需要定义角色/策略以及相应的登录重定向路径。我们可以在Startup.cs文件中添加以下代码：

services.AddAuthorization(options =>
{
    options.AddPolicy("Admin", policy => policy.RequireClaim(ClaimTypes.Role, "Admin"));
    options.AddPolicy("User", policy => policy.RequireClaim(ClaimTypes.Role, "User"));
});

services.ConfigureApplicationCookie(options =>
{
    options.LoginPath = "/Account/Login";
    options.AccessDeniedPath = "/Account/AccessDenied";
    options.Cookie.Name = "MyAuthCookie";
    options.Cookie.Path = "/";
    options.Cookie.HttpOnly = true;
    options.ExpireTimeSpan = TimeSpan.FromMinutes(20);
    options.SlidingExpiration = true;

    // Define a custom CookieAuthenticationEvents class to handle events.
    options.Events = new CookieAuthenticationEvents
    {
        OnRedirectToLogin = context =>
        {
            if (context.Request.Path.StartsWithSegments("/api") && context.Response.StatusCode == (int)HttpStatusCode.OK)
            {
                context.Response.StatusCode = (int)HttpStatusCode.Unauthorized;
            }
            else
            {
                context.Response.Redirect(context.RedirectUri);
            }
            return Task.CompletedTask;
        },
        OnRedirectToAccessDenied = context =>
        {
            if (context