After ordering the products, you have to log in, click on the YOUR ORDERS menu item on the top-right corner, then choose the order number, and click on the file name in the files column to download the file. Don't worry about unfinished orders, you can start the ordering process from the beginning any time.
The differences between the professional and the free versions are generally the number of module positions, number of color schemes, the dropdown menu, the image logo option, additional blog layout, +2 module styles, and for version 3.x the number of social icons.
The product pages generally have a link to a page that contains instructions about setting up the template, like parameters, module positions, menu setups. You can also find these instructions on the demo sites, just click on the top menu items of the demos.
a4joomla.com is not affiliated with or endorsed by the Joomla! Project or Open Source Matters. The Joomla! name and logo is used under a limited license granted by Open Source Matters the trademark holder in the United States and other countries.