RGB volume rendering with cropping

Hello everyone!
I have been trying to execute “RGB volume rendering with cropping” provided by PerkLab Research in the YouTube link https://youtu.be/xqkYKUj51gQ?si=hWH71cuokmJsgqOD
However, I was not successful in any of my attempts. I am providing the steps I executed to perform RGB volume rendering with cropping.
Please correct and guide me so I can execute as provided in the YouTube video.
Thank you.