.net core 6 SSO(Single Sign On) implementation

Question

In .NET Framework MVC we can implement SSO (Single Sign On) Application by using Form Authentication in Web Config file. Please Note : I have already created domain in IIS server with 1)www.mainapplication.com => Having log in mechanism 2)www.secondapplication.com => this will be redirect to mainapplication login page if user is not logged in, below example is with

<authentication mode="Forms">
    <forms name="SingleSignOn" 
             loginUrl="www.mainapplication.com/account/login" 
             timeout="480" 
             slidingExpiration="false" 
             enableCrossAppRedirects="true" 
             path="/" 
             domain="mainapplication.com" 
             cookieless="UseCookies">
      </forms>
</authentication>

Now I want to implement same with .NET Core 5 or 6

What I have did so far as described below. in Program.cs (mainapplication)

builder.Services.AddDataProtection().PersistKeysToFileSystem(ProgramService.GetKyRingDirectoryInfo()).SetApplicationName("SharedCookieApp");
builder.Services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme).AddCookie(options =>
{
    options.LoginPath = "/Account/Login";
    options.Cookie.Name = ".AspNet.SharedCookie";
    options.Cookie.Domain = ".mainapplication.com";
});
builder.Services.ConfigureApplicationCookie(options =>
{
    options.LoginPath = "/Account/Login";
    options.Cookie.Name = ".AspNet.SharedCookie";
    options.Cookie.Domain = ".mainapplication.com";
});

mainapplication Log In code

[HttpPost]
        public async Task<IActionResult> Login(string email="") {
            var claims = new List<Claim> {
                 new Claim(ClaimTypes.Email,"user.test@email.com")
            };
            var claimIdentity = new ClaimsIdentity(claims,CookieAuthenticationDefaults.AuthenticationScheme);
            //var authProperties = new AuthenticationProperties
            //{
            //    //AllowRefresh = <bool>,
            //    // Refreshing the authentication session should be allowed.

            //    //ExpiresUtc = DateTimeOffset.UtcNow.AddMinutes(10),
            //    // The time at which the authentication ticket expires. A 
            //    // value set here overrides the ExpireTimeSpan option of 
            //    // CookieAuthenticationOptions set with AddCookie.

            //    //IsPersistent = true,
            //    // Whether the authentication session is persisted across 
            //    // multiple requests. When used with cookies, controls
            //    // whether the cookie's lifetime is absolute (matching the
            //    // lifetime of the authentication ticket) or session-based.

            //    //IssuedUtc = <DateTimeOffset>,
            //    // The time at which the authentication ticket was issued.

            //    //RedirectUri = <string>
            //    // The full path or absolute URI to be used as an http 
            //    // redirect response value.
            //};
           
            await HttpContext.SignInAsync(CookieAuthenticationDefaults.AuthenticationScheme, new System.Security.Claims.ClaimsPrincipal(claimIdentity));
            return Redirect("/");
        }

Second Application (Program.cs)

builder.Services.AddDataProtection().PersistKeysToFileSystem(ProgramService.GetKyRingDirectoryInfo()).SetApplicationName("SharedCookieApp");

builder.Services.AddAuthentication("Identity.Application")
                .AddCookie("Identity.Application", option =>
                {

                    option.Cookie.Name = ".AspNet.SharedCookie";
                    option.Cookie.Domain = ".mainapplication.com";
                    option.Events.OnRedirectToLogin = (context) =>
                    {
                        context.HttpContext.Response.Redirect("http://www.mainapplication.com/Account/Login");
                        return Task.CompletedTask;
                    };
                });

builder.Services.ConfigureApplicationCookie(options =>
{
    options.Cookie.Domain = ".mainapplication.com";
    options.Cookie.Name = ".AspNet.SharedCookie";
    options.Events.OnRedirectToLogin = (context) =>
    {
        context.HttpContext.Response.Redirect("http://www.mainapplication.com/Account/Login");
        return Task.CompletedTask;
    };
});

So when I trying to access second Application (in case of user is not signed in), it is being redirected to mainapplication : (http://www.mainapplication.com/Account/Login), after successfully logged in, again I trying to access second application, it won't authorized user and redirected to mainapplication login screen.