购买意铁问题，急

昨天买了意铁的票子，发来一个PDF文件，底下有这么句话

ATTENTION: this payment receipt is not valid as a travel ticket as it relates to a ticketless purchase.

To register your presence on board, please notify the ticket code (PNR) to the train personnel.


是不是不能当做车票使用啊，那我怎么上车啊？