自身でプリントもしくは窓口でチケットを受け取る？

経験者ではありませんが、メールが送られてくるのではなく
自身でプリントアウトするか、予約番号とパスポートを窓口
で提示すればＯＫではないでしょうか？

7.2 After completing payment, please be sure to print the ticket as evidence prior to boarding the bus.
7.3 Alternatively, customers can collect their ticket at Nakhonchai Air service stations. Please state the Payment Reference Number and provide a proof of identification (Thai National I.D. card or Passport). In the case of appointing a representative to collect the tickets on your behalf, please provide a photocopy of your Thai National I.D. card or Passport and complete the ticket collection form, which can picked up from our ticket office.