Make sure you have the latest version of the Gifted app. Sometimes, the Gift Card (link) may not open in the app due to a poor WiFi connection, WiFi restrictions, Content/ ad-Blockers or App restrictions.
You can also try closing any unwanted programs that are running in the background, as this will free up your device's available memory.
If none of these options work, please reach out to Gifted Support for personalised assistance.