Hi,
After you purchased Small Business Edition you might have received email communication from Symantec.
Email may contain new serial number to download the product.
If you don't have any communication with regards to the same then please contact reseller or business partner.
Even you can contact Symantec license department.
United States: https://support.broadcom.com (407-357-7600 from outside the United States)
Follow the IVR & get connected to the license department.