I applied through their website. I first got emailed by RRHH saying that I had to solve a CTF exercise. I solved it and emailed it. Then I got emailed again telling me to solve a blockchain challenge. I solved it, emailed it and had to remind RRHH about it because I was not getting any feedback after two weeks. Then they replied and scheduled an interview with a guy named Luis. He was friendly, asked me a few questions and I answered most of them correclty. He also made me go over my solution of the blockchain challenge. Once again, I was not getting any feedback after two weeks so I emailed RRHH and they told me they were not moving forward with me. I wish I had gotten some real feedback on why I failed. It could be that they were looking for someone more experienced but in that case they should have ruled me out earlier instead of making me lose a lot of time with all the challenges.