Spirit makes this stuff way more confusing than it needs to be. The two free checked bags benefit usually only kicks in once your card is fully approved and linked to your Free Spirit account, and it typically applies when you use the card to book the flight. It’s not automatic at booking if the system doesn’t recognize you yet.
If you weren’t instantly approved, that doesn’t automatically mean you lose the sign up bonus you clicked on. Most of the time, as long as the application eventually gets approved, the original offer sticks. But with Spirit and their bank, it’s definitely something to double check.
As for using the card, you usually don’t need the physical card in hand. Once approved, you can often add it to a digital wallet or see the number in your account and use it right away. The bigger issue is making sure your Free Spirit number is attached so the bag benefit shows up.
Classic low cost airline chaos.