Use the credentials you received (directly or via an external website) and log into the account. Make sure that the content on the account is correct (correct edition of the game, no playtime etc) Change the credentials to make the account your own: Change the email Change the password Add 2FA The account should be used as a way of accessing the game/content you are interested in. It is not recommended to use it as your main account, as you might have issues with making purchases on it.