check that I was a real person.
Any service that asks you to do this is a scam, even if it is a reliable service. There are thousands of parties to prove that you are the owner of the account, and sending money is not one of them.
Sorry for your loss. Most likely, the scammer (site owner) is the one who bought Summoners War from you. It seems that he convinced you to use this service as a guarantee. Unfortunately, it seems that you have fallen victim to this scam. He did not send you $4,300, so add the information for that account because it is definitely the scammer.