How do you let the player create their own username and let it show on a scoreboard?
You’ve asked an incredibly broad question here so let’s narrow it down a bit.
Is this scoreboard just an in game mesh or do you mean a scoreboard like an online leaderboard viewed in a UI or website?
Is there any existing infrastructure for player data? (Are you trying to figure out how to pull a name from a database or just how to get a UI to type a name into?)
In my system I have the player enter their username when they login to the server. Username is stored in GameInstance on the client. Once logged into the server the username is sent to the server via RDP and stored in a custom PlayerInfo class.