Nowadays, most people restore their apps from old to new phone.
If this is the case then SecureIdentity app will not work. This is a security app that hold your digital identity. Backup and Restore will not work.
Delete the app and go to Play Store or App Store and download the up-to-date secureidentity app.
Click on Open button at the Play Store or the App Store. Then
Open a browser and visit https://secureidentity.co.uk/ - My Account - Changed Mobile -then follow on the screen instructions.
Ideally you should use a dual device option. One to start the browser session and the other to download and set up the secureidentity app on it