Permission Denied, Conversion Shutting Down, Not Able to Run FastFlix in macOS

Hi all,

I am not a software engineer and therefore very limited in troubleshooting software compile and terminal error.
I tried to install FastFlix in my 2 MacOS, in 10.14.6 and 11.5.1 but not able to run despite already (1) putting the file as executable, (2) downloading ffmpeg and ffprobe and putting the directory of both in the FastFlix.yaml file, (3) putting necessary permission for Terminal to have full disk access, change ownership of where I put FastFlix folder, running with sudo, etc.
Following is the screenshot. Need help on how I can solve this. Somehow, way few months back, I was able to run FastFlix successfully on my 10.14.6 machine, but back then I reinstalled my system and never use FastFlix anymore until today when I got stuck in this error. Thank you in advance for any advise.