The download is in the form of a Disk Image (.dmg file). Once it has downloaded, double-click to "mount" it as a virtual disk, and examine the contents, which include one or two Applications, corresponding java executable files (jar files) with the same names, a manual, and a couple of small files containing important information.
If you want to use Apple's legacy Java 1.6 to run the software as normal Mac applications, drag them to the Application folder, then drag the manual to a suitable place. The applications will not work with Oracle's Java; you need to drag the corresponding jar files to a convenient place, and double click them as if they were applications. They contain exactly the same Java executable code as the Mac applications. You can check, via the "About" dialog, what version of Java is being used once the application starts up.
You should get messages from the system asking whether or not to trust the application(s). Be sure to read the security information on my site.
I do not have a license retrieval system. The first couple of uses after you enter the license code, the About Box will appear and prompt you for 10 seconds to print (and keep safe) the information. The About Box may be used in this way at any time, except after your computer has crashed, or been disposed of!