Mindbody Visual Designer interview questions

It's quite a long process. I went through 5 interviews - one with HR, then with the immediate supervisor, then there were 3 panel interviews of 30mins each. There was also a cognitive test and a technical test to create a landing page and paid ad following their brand guidelines. The interviews were pretty straightforward and all the people involved were very kind and welcoming. I got through the final interview after almost 4 weeks of the process, and received an email 7 days later stating they had chosen another candidate. No problem there, but I did send an email to HR asking for feedback, after all, they had plenty of time to know me and pinpoint what I could've done better. I got no response whatsoever. That was pretty frustrating after such an extenuating process.