If you bought the game legally (via Steam, Epic Games Store, or Rockstar Launcher), there’s no .rar file or password. You just install it normally.
If you see a Red Dead Redemption PC .rar asking for a password, treat it as a high-risk file . No password is worth your security.
It sounds like you’re looking for something related to a of Red Dead Redemption (likely the first game, since the PC port was only officially released in October 2024) — specifically a .rar file protected by a password.
Here’s the important, direct answer: