Hello 22lhayes,
Thank you for using Apple Support Communities! I understand that you're wanting to know if there's a way to recover your game progress for DoubleU Casino after migrating from an iPhone 6 to an iPhone 11.
If your account was connected to Facebook on the iPhone 6, try connecting to the same Facebook account in the game on your iPhone 11 under Settings. If the game was not connected to Facebook but you still have access to the iPhone 6, you can try going to Settings within the game. Tap on Info next to where it says Switch Device. This will allow you to generate a code which can then be entered on the iPhone 11 to transfer your game progress.
If you're not able to transfer your game progress to the iPhone 11 using either of those steps, you'll want to reach out to the app developer for additional support:
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Take care.