The login in ASP.NET Core (Model-View-Controller)

Question

I would like to write login process but I get some errors, please help me solve these problems.

[HttpPost]
public async Task<IActionResult> LogIn(LoginVM loginvm, string? ReturnUrl)
{
        if (!ModelState.IsValid)
        {
            return View();
        }

        AppUser user = await _userManager.FindByNameAsync(loginvm.EmailOrUsername);

        if (user is null)
        {
            user = await _userManager.FindByEmailAsync(loginvm.EmailOrUsername);

            if (user == null)
            {
                ModelState.AddModelError("", "Username-Email or Password is incorrect");
                return View();
            }
        }

        var result = _signInManager.CheckPasswordSignInAsync(user, loginvm.Password, true).Result;

        if (result.IsLockedOut)
        {
            ModelState.AddModelError(string.Empty, "Try it after few seconds");
        }

        if (!result.Succeeded)
        {
            ModelState.AddModelError("", "Username-Email or password is wrong");
            return View();
        }

        await _signInManager.SignInAsync(user, loginvm.RememberMe);

        return RedirectToAction("Index", "Home");
}

The last thing login.remember me I think faces to some problems here can you help me to configure login process again, when I run it throws an exception