Ideally, you should get the Serial Number from the seller and Register that (he/she may need to Transfer it to you) so that you can download the driver.
Otherwise, please contact
Sales/Account Support, via here. You will be able to search the FAQs first, but if they do not resolve your issue, there is a link at the top of the Search FAQs page to a Support form. Sales Support can advise you on what can be done.
Response time normally is within 2 working days (US (East Coast) Business hours, generally), but in the current circumstances please allow some more time. Administrators and Moderators here cannot access your Account.