Milestone Technologies Fullstack Software Engineer interview questions

I went through a phone interview, a call with HR, and a technical call, only to then receive an assignment that took me around 6-8 hours, during which I tried to give my best. The next day, I got a call saying, "we're sorry, but you didn't meet the requirement," without any further details. It's great that I can spend hours on interviews and assignments, but they only spare a minute to give me feedback.