AppsFlyer Software Engineer interview questions

Sent resume to a friend who works there. A week after I had a phone interview with HR, which led to a 90 min. technical interview. Due to an offer I already had, the next stage was an intense day with 4 interviews in a row (3.5 hours, which included an additional technical interview, HR, VP, CEO). A response came 2 days afterwards.

I applied via LinkedIn and was contacted by HR. I had to come 3 times: 1. Technical interview 2. Another technical interview + interview with HR 3. Interview with VP R&D and interview with CTO At both technical interviews I was explained about the company and the job and was asked to tell about myself and my latest project. We discussed it a bit and after that I was asked one technical question. Both technical questions were very fair. Not something too difficult. VP R&D and CTO also requested to go over my latest project and asked follow-up questions. The interviewers were very pleasant and made a great impression on me, both professionally and personally. At the end they decided it wasn't a good fit. I asked HR if they could maybe explain their decision. She was super nice and actually asked one of the interviewers to call me. He was very helpful and actually gave me points to work on. This is rare for a company to be so open and willing to help and I really appreciated this! AppsFlyer seems like a great place to work!