Your issue is a frequent topic in our community. If the e-mail confirmation was not received, and you also checked your SPAM folder, then the purchase was not sucessful. The amount reserved on your credit card will again be released after a few hours.
Please buy the ticket again. Kindly make sure your credit card supports 3D secure ID. You may wish to buy it with Trenitalia in case the problem persists on the SBB platform.