How i can restrict the Authorize attribute to certain users only, inside my asp.net core mvc web application

I have created a new asp.net MVC core web application and i set it to use organizational account as follow:-

now if i add [Authorize] attribute to an action method then the user will be asked to login first. but my question is how i can only allow certain users to access the action method?

second question, is how i can prevent users from logging to the application unless they are inside a predefined list?