All Terminal codes given do the job for you. You don't have to actually add an extension to the file to kind of accessing to a text file. Type Terminal code that's it you have each time an action : do that on that file and copy it next to that path... The full FIX from @esperdiv is here (i only suggest than as we have an uninstaller and over bridge we don't so much need to backup the original kext which is entirely up to me... BUT I'M WRONG THERE WE NEED TO APPLY THE FULL PROCEDURE)
(all happen in the Mac Terminal app found in utility)
Open the Terminal app.
(so what he suggest is to backup the kext file first from the original path to the path who lead to the desktop but actually this action copy-paste in the terminal execute the code and DO THAT action you will see the copied backup file on the desktop)
sudo cp -a /Library/Extensions/ElektronOverbridge.kext/Contents/MacOS/ElektronOverbridge ~/Desktop/
(then the code will extract the 64-bit portion of the kernel extension and copy back to the path where the kern files of the OB driver reside in extension system folder)
sudo ditto --arch x86_64 ~/Desktop/ElektronOverbridge /Library/Extensions/ElektronOverbridge.kext/Contents/MacOS/ElektronOverbridge
Dont worry about what it does type exactly as is in the Terminal and Let go OB working then