The download code for Stitch Era Universal is written on the application's official download page. It's posted right above the orange Start Free Download button. In my browser, 1234575-ABCDL is listed as the download code, but there's a very slim chance that it varies based on IP or date, so you should check it out for yourself.
In case you need any additional help, there's also an official guide for downloading, installing and activating the application, which I recommend checking out.
Later edit: I've visited the page on another PC from another network and the download code is the same which means you can use it.