This could be for a number of reasons Maybe the Credit card lodged a suspicious activity if you have been new using your card and have made a few back to back purchases. Or maybe a number has not been entered correctly.  Did you attempt the transaction again in 30 minutes as the notice said and what was the result ?

I know  I have gotten calls at times from my CC after getting packages for more than one castle on different servers. Once I contacted the card company and they said they are just cautious and they never gave me trouble again. 

Please let me know  if all has been solved  or if you need more help ?

I also notice this is a Rise Of Balur Package this is the Stormfall Age of War forum I will move this where it belongs  into the Rise Of Balur forum 

And here is a link to support add the screen shot to your support ticket in the appropriate  place please.

https://social-support.plarium.com/hc/en-us/requests/new?ticket_form_id=168205&fbclid=IwAR0rWnxKHZXxrhNSqGsDh5tWogavQUynr71DjYNrXsDMhOFcMi43vv6tGvc