Need advice for interview and landing a job

Hi everyone, today I gave an interview at KPMG it was final round with one of the directors but the questions started going off track from asking me about my introduction to asking about what paulo alto does and we went on discussing that, he didn't like my answers ended up rejecting me, I fumbled. Ps. I have a background in Cybersecurity as an internship for 1 year, I am in my final year of btech IT at dj sanghvi, and also completed diploma in engineering, I need advice on how to land a job off campus in android development, also I fumble a lot during my interviews so if you guys can share how to not fumble at an interview