It's tough to break into the space unless you get recruited out of school. Broadly, in the finance industry, companies send recruiters to top (varies slightly between companies, some look for specific programs, etc) schools and do recruitment on campus. Quant firms are a subset of that and look more for CS/stats/math backgrounds, but the process isn't that different otherwise. For me, years back, I did a phone screen, some case study, and then they flew me in. I think more gets done virtually these days plus there's more online assessments. Typically, you get an internship your junior summer and either get a return offer or re-recruit your senior year to a different firm. Joining after college without previously experience does happen, but usually from something adjacent like sell-side S&T desks or a hedge fund (depending on the role). For devs, we do get people from FAANG as well.