1. Go to iOS Settings > iCloud and tap "Sign Out" on both devices.
2. Log back into the Apple account on the device with the game progress you want to use (#1).
3. Launch KoT on device #1.
4. Make sure iCloud synchronization is turned on in game Options.
5. Log into the same Apple account on another device (#2).
6. Launch KoT on the device #2.
7. Progress restoration message should pop up. Tap "Yes".
If you are still unable to play on another device under the same account, please check all cloud save settings and make sure that it is enabled on both devices. Also, check whether it is possible to restore the progress on some other iOS device besides the one you try to transfer progress to.