Since this is a digital code, you can purchase it and get the redeem code for the $100 in PlayStation Store credit right away. As you won’t have to wait for it to arrive in the mail first. Once it’s been redeemed, you can use it for anything you want to buy on your PS4 or PS5. Whether that’s games, DLC, or add-ons. You could even use it to pay for PlayStation Plus if you wanted to.