Pitch Technical Support interview questions

The screening with HR and interview with Head of the department were quick. After that, received a hometask with one week deadline. Didn't access to their platform to perform the hometask for couple of days. With 4 days to meet the deadline, I managed to finish and send the hometask back. It took 1 month for them to give me feedback after couple of follow-ups & mixed-up internal communication, was told that I wasn't selected. Didn't give constructive feedback or anything. Just that "we've not decided to move forward". Please provide detailed feedback about what you've expected and what the candidate didn't meet. It will justify the decision to the candidate as well.