Here are the steps to redeem your Starbucks vouchers:
1. Once you have purchased the voucher, proceed to open the Starbucks app and sign in.
2. Click on "PAY" and then "ADD CARD" in the main section.
3. Enter the card number and security code from your voucher link and click "Add".
a. Card number - code
b. Card security code - activation pin
4. If you're having trouble logging in, make sure you have the latest version of the Starbucks app.
P/S Note that you can only add up to 50 cards in the app, so delete old ones if you need to add more.