Yoyo-powered loyalty cards can be linked to the app whilst you are creating an account. Just follow the prompts on your screen when creating an account. If you link your card during the registration process, you will be able to carry on using it to collect loyalty and will see the rewards you accumulate in-app.
The loyalty you accumulate on Yoyo-powered loyalty cards can also be transferred to the app if you already have an account via the Setting menu > Add a loyalty card, where you will be prompted to scan your loyalty card and enter its 3-digit PIN. However, please note that if you link a loyalty card afterwards, the card will be deactivated once your loyalty has been transferred. To continue earning loyalty you will need to transact via the app by scanning the payment QR barcode in your app at the till 🎉.