I think you need to build it from the source code which is here:
https://www.fosshub.com/DVDStyler.ht...er-3.1.tar.bz2
I've done this for ffmpeg on a Mint machine when I needed an older version to check something out.
It's not complicated, just follow the installation instructions to the letter and make sure all the dependencies are in place - you'll probably find the install (it's actually a make process, man mak and man install may help) will fail as it finds thing missing.
And this was the main page that I found
https://www.dvdstyler.org/en/
Good luck