They may have a limit on the number of licenses that they are willing to give away. You might try again later to see if it changes.
However, this offer differs substantially from most GOTD offers where you can install today and then test/use at your leisure some time in the future. Unless you have an immediate need for the software, and have the new PC on hand, the software won't do you any good. You need to install it on both computers and you can't install the GOTD offer after today.
It's a good advertisement for what's available but for most downloading it's probably not any different from the trial version that's available on their website. You can see what it would attempt to do but you can't determine what it will do unless you have a PC ready to receive the transferred programs.