http://alf.nu/RegexGolf?world=regex&level=r00
took me 25.75 seconds, including learning how the website worked. I actually solved it in ~15 seconds, but I hadn't realized I got the correct answer becuase it was far too simple.
This website is much better https://regexcrossword.com/challenges/experienced/puzzles/e9...
Also this is the easiest starter puzzle, once you solve it you can click through to the next ones with increasing difficulty.