I find this announcement fascinatingly incomprehensible; it clearly emerges from a slice of the software universe quite distant from mine. The use of the acronym "CTF" suggests that the authors are very familiar with this genre of game; but how exactly does it work? What does it have to do with programming? I guess they are making programming into a game (?) and this somehow has something to do with hiring?
A CTF is a game that one plays by programming. I wish I could point you to competing CTFs that you can sign up and play right now, but most disappear from the Internet because they are fiendishly difficult to keep running. Ask me (or any team that has shipped one) why if you're curious. One example would be MicroCorruption. https://microcorruption.com Thomas and Erin helped build it back when they were still at Matas…
Or, much more commonly, it's a popular game mode in any number of multiplayer games. You're using some really niche jargon without properly qualifying it.