I applied online. The process took 3 weeks. I interviewed at NIH in Feb 2018
Interview
1-hour phone call interview with 6 member panel. Mostly the questions are regarding former research experience. Also the knowledge of the current state of the current methods. Given a sample problem and was asked to explain my approach to solve the problem.
Just one round of interview with the PI and it is not very hard. You need to prove your ability to lead scientific projects alone and show creativity. You also need to show that you are a good person.