I just downloaded and installed HitFilm Express 4, and it is working so far in Vegas Pro 14, build 201.
I didn't have to do anything to get a license other than post a comment on Google. That allowed me to download the software. After installation, I ran the program and was presented with the option to "Activate," "Get Free License," and something else. I clicked the Activate button and signed in to my HitFilm account, and that was it. I first tried clicking on "Get Free License," but that just took me to the download page. I lost the page for activating, so I had to go through the menu to get the Activate page again.
Gateway DX4860-U28 i5-3300 Quad Core 3.0 GHz, Intel HD 2500 graphics, 8 Gb RAM; 1 TB 7200 RPM, 10 TB External, Windows 10 (x64).