Downloading your products and receiving your license key should be automatic, as the the relevant information is forwarded to you immediately via e-mail.
If you'd like to manually download your products and obtain your key, you can visit the vendor you purchased from, login with your STORE account and view your order details.
The vendor links are:
HiFi Software Marketplace (http://www.hifisim.com/shop)
SimMarket (http://www.simmarket.com)
Download links and keys are usually available only for a limited time. If you need to re-download or obtain your key after 3 days from purchasing, please contact the vendor with your associated order # and purchase information.