Discover is offering a new $15 promotion simply for setting your Discover card as the *default* payment method. You should see the promo immediately after activating. I recommend to keep Discover as your default method for that next purchase using the $15 promo credit; you’ll get 5% back as well during this quarter.
If you don’t already have your Discover card linked, try this link for a different $15 bonus for adding your Discover Card to Amazon as a payment method.
This is separate from the Discover Shop with Points promo, where you actually redeem your Discover cash back rewards on an Amazon purchase.
Finally, try this link to see all your Discover + Amazon offers.
This is a recurring perk for existing Discover cardholders, which is why I never cancel a card with no annual fee. Check out my Discover it credit card review, one of my keeper 5% cash back cards. From now until December 31, 2024, Amazon is one of their 5% categories.