Interacting with the user that logged in,How to work with the User that logged in

I am doing a simple school project where I have to build a game, register the user, log in, and save scores. Since it’s a simple school project, I do not need a database like SQL, so I am saving all of the information into a text file (Users, Passwords, Scores). I made a Login, where if they enter the correct username and password, it initiates SceneManager.LoadScene(Game).
That just brings me to the game, It does not save the person that logged in (I cant really explain it that well). ,

Before loading the “Game” scene, store the name of the logged in user with PlayerPrefs.

PlayerPrefs.SetString("LoggedInUser", name);

Then in your game scene, in the script that needs to know who is logged in, do this…

String LoggedInUser;

void Start() 
{
  LoggedInUser = PlayerPrefs.GetString("LoggedInUser");
}

You can save and read the score this way as well with SetInt and GetInt

Hope this helps,
-Larry