Howdy Guptaso,
Thanks for participating in the Apple Support Communities!
While this may need to be directed to PeakFinder Support, let's see if the following steps may help before reaching out there. The steps below speak to redeeming gift cards; however, you may be able to redeem the code with the same steps so give it a try. You can locate additional steps for other devices here: How to redeem your Apple Gift Card or App Store & iTunes gift card
Redeem a gift card with your iPhone, iPad, or iPod touch
1. Find the 16-digit code on the back of the card. For some gift cards, you might need to peel or gently scratch off the label to see the code.
2. On your iPhone, iPad, or iPod touch, open the App Store app.
3. At the top of the screen, tap the sign-in button
or your photo.
4. Tap Redeem Gift Card or Code. If you don’t see Redeem Gift Card or Code, sign in with your Apple ID.
5. Tap Use Camera and follow the instructions on the screen. If you have trouble redeeming the card, tap "You can also enter your code manually," then follow the instructions on the screen.
6. Tap Done.
If those steps don't work, reach out directly to PeakFinder support to check if this is available with the App Store. If so, Contact Apple Support directly to have this looked into in more detail.
Have a great day!