Identity Server 4 vs asp.net idenity

Question

HI I am using the asp.net core identity in my current project. While I was working on it, I read that it is not a security system rather provide login/logout and user profile.

So now I have two questions.
If it doesn't provide security then why we use it to secure our website. I think I am okay to use asp.net. core identity because user can be register first and login/logout, I can provide the authorization, and some other functionality such as forget password and email verification.

Now I have 2nd question.
If I use the Identity Server 4, does it provide the built-in code /views for user management, roles, email recovery provided by Identity server 4?