Notification say: "Savings In Bloom -  Spend $20 and Save 20% - code MAYUSAVE20 at checkout. Coupon valid until Thursday 5/14/2026, 11:59 PM (cdt). Coupon is stackable on other promotions but may not apply to all products."

Since coupon is stackable on other promotions, then there is no valuable reason that it don't work on this one, and "may not apply" generally only refer to "red coupon flag", especially since last year at least, that coupons also works on prime products.

So frankly, if coupon still not work on 14th, then I empty cart and so no money for Renderosity, as simple as that.