Having trouble booting from external usb 3 SSD

I do apologize. I will make sure to post in the correct section from now on.

Im reading in order to get petitboot i need to follow these instructions :

https://wiki.odroid.com/odroid-n2/software/building_petitboot

I SSH into my box with a fresh install of coreelec on my micro sd.

The first step directs me to type in :

source buildroot/build/setenv.sh odroidn2_bios_release

however, I get an error that no such directory exists

Is there a simple way I can download the petitboot image (which I read I have to place on the first partition of the micro sd from my understanding)

Thanks!