AppsFlyer Customer Success Manager interview questions

I applied via AppsFlyer employee through LinkedIn. After two days, I received an email where I was asked to send a short video about my professional experience and my understanding of AppsFlyer. I sent the video at the same day and on the next day I received a call from the HR. She said they really liked the video and would like to continue to the next step - Team Leaders interview. I had an interview with two Teams Leaders via Zoom. The interview took about an hour. They asked about my professional experience, my understanding of the Customer Success Manager role and other questions that I mentioned below. They also asked situational questions about the customers (for example, how would I make unsatisfied customer to stay). Team Leaders willingly told about the position in details, I also asked various questions and they were happy to answer. In the end of the interview, the Team Leader told me about the next steps of the process: Home Assignment ---> References---->HR Interview -----> Final Presentation with C-Level (I could missed something else, but I mentioned the main steps here). Overall it was a very pleasant and detailed interview. After two days, I received the call from HR. She said the Team Leaders provided a positive feedback regarding the interview and they would like to move to the next step - Home Assignment. Then she sent me a Home Assignment that was a really big one. It consists of the questions about the AppsFlyer, situational questions and technical questions. I had about 72 hours to complete the assignment. I also had to write my answers to each question in two languages, since I applied to Customer Success role that demands knowledge of English and additional foreign language. The answers in each language took 7-8 pages, so my assignment consisted of 15 pages overall! It was a really intense assignment where I had to research a lot about the company and the product. I made my best to give the detailed answers and was sure I will move forward to the next step. In 2 days after submitting the assignment, I received a call from HR. Her words were a total surprise for me - "We reviewed your assignment and regret to inform you we decided we will not continue to the next step". When I asked her if she could specify the reason, she said they didn't feel I have enough CSM approach. This short answer was a pretty frustrating. In my opinion, when a candidate submits such a complicated assignment that demands a lot of work and research, the feedback should be much more detailed and personal. At the same time, I do appreciate the fact that the response was fast and the HR lady chose to call me instead just sending an email which I assume is not easy when you have to inform the candidate about such unpleasant news. The overall experience is pretty positive, however I would definitely recommend to HR Team improving the feedback process, since it's a crucial part for the candidate.