Slack QA Automation Engineer interview questions

On a Monday I had an initial phone screen, then I was sent a coding challenge the same day. I had a week to complete the challenge. I submitted it 4 days after receiving it. On the next Tuesday I received a call informing me my solution was not good enough. My solution worked, my guess is that I just wasn't doing things good enough. I have work experience with QA automation but none with web automation. Hopefully this explains the gap in my knowledge. I guess they were nice for letting me even try!