Here is a simple step-by-step instruction of how to redeem your fresh promo code and get the app for free from Apple's App Store. All you need is the promo code and sign in to your Apple ID.
On your iPhone, tap the App Store icon to open it.
Tap your profile icon in the top right corner of the App Store.
Scroll down and tap 'Redeem Gift Card or Code'.
Enter your promo code in the field provided and tap 'Redeem' in the top right corner.
Confirm the redemption and the Saving+ app will begin downloading automatically. Open the app and start earning more from your savings!