In order to redeem a gift card, it's not necessary to enter your credit card info. Just make sure you're typing the code directly in this page and not the regular Premium checkout page, as the latter will ask for card details to start a subscription.
Hope this helps. If you need anything else, the Community will be here.
Help others find this answer and click "Accept as Solution".
If you appreciate my answer, maybe give me a Like.
"Music touches us emotionally, where words alone can't." -Henry Thoreau