There is a pinned post on this forum providing the answer to your question: Authorized credit payment but cannot receive the ticket
I do not know why you conclude the payment was successful, for me, the error message is straightforward. Your money has been reserved by your bank only and will again be released in the next hours, please check your credit card account once more. There was no payment to SBB at all. For further questions, you have to contact your bank.
International transactions may fail because customers use credit cards which do not support the security standards for online shopping applicable in Europe. For a successful payment, you should use a credit card that supports 3D security.
If you are, by any chance, about to buy the Swiss Travel Pass, you can also get it from here, their webshop is less restrictive: Swiss Travel Pass | Switzerland Travel Centre