The email says:
Use Apple Pay in the StubHub app to get $10 off your purchase of $100 or more. Enter code PAYFASTER during checkout, through October 31.*
*To redeem, enter code PAYFASTER at checkout. Offer valid on a single order, excluding gift cards. Must check out using Apple Pay in the StubHub app by October 31, 2019. Offer redeemable once in the U.S. only. Cannot be combined with other offers. No cash value. Offer is non-transferable. StubHub may modify or discontinue offer without notice. Void where prohibited.