hi
First it is not a big problem just modify kext on your hardware e6520 i think there is your problem
Second the line
softwareupdate --fetch-full-installer --full-installer-version 11.6
Is for all who have problems in download macos if you want monterey for example just change the number to 12
It is a great solution for dwnloading a clean and full macos
Good luck and thank you