Why isn't my data trasfered from my first device to my second device?

Data is synchronized via your personal iCloud. So please make sure that you have enabled this and that you have enough storage space in your iCloud. Also, please enable the iCloud Drive functionality in the iCloud settings if it is still disabled.

The synchronization of the data happens in the background when the operating system has little to do. A permanently active power saving mode, poor internet connection or even a full device storage can cause the synchronization to be delayed. These are circumstances on which I, as an app developer, have no influence, but are determined and regulated by Apple.

Experience has shown that actively closing the app via the app switcher and then restarting the app can speed up the synchronization.

If all this does not help, I would be happy if you could contact me by mail.