Indeed interview questions

The interview process had an initial screening round which is an hour video interview call. They asked one easy-medium Data structure problem and some case study to test our understanding on some metrics and our though process. After I successfully completed this, I had a final interview that had around 4 rounds . The final interview in my view seemed to have went well as, I pretty much answered all questions but, any how I didn't get selected. The issue that I had with this interview is that the role I was first contacted to be interviewed for is a Product Developer role. I got an email from Indeed after four days of the final interview saying that I have not been selected for Research Engineer Level II role. I wish I had a better understanding from them on the role and their expectation because this is really confusing. I emailed the HR as well for this clarification, but they never replied back which I see as a negative here. I feel that they owe me an explanation on this confusion regarding the role as I'm left out thinking what might have happened back there. When I am spending this amount of time on getting interviewed, I would at least like to know why this confusion happened in the first place.