As of January 18, 2023, Google's Stadia service has officially ended. You can read more about their announcement and FAQ here: https://support.google.com/stadia/answer/12790109
Any refunds, returns, or exchanges for the Stadia platform will be handled by Google directly, 2K will not be able to provide replacement keys or refunds for Stadia purchases. Unfortunately, saves and progress for 2K games on the Stadia cannot be transferred to other platforms.
For any other questions or concerns, you can review the Stadia Help Center at https://support.google.com/stadia and at the bottom of that page are the ways to connect to further support from Google.