How do sellers on eldorado get the accounts?

I bought an account and logged in with ease, And was unable to change the email and password due to 2fa, the account details on eldorado included an email account with password and also a link to the email website, on the website (which was Russian) I entered the details to log in and it was correct but then it asked me to supply a Russian phone number which I don’t have meaning I can’t change the email or password on epic games

Or is this just an account configured by the seller beforehand?

Can the original owner of the account still access?