I was able to follow your instructions line by line…
Just to clarify though, when you say:
Now we need change another file.
nano /opt/retropie/configs/apple2/startlinapple.sh
Do you mean we need to create a new file?
Aside from that, everything went smooth. All the ROMS show up under the Apple II however when I try to run anything, I keep getting booted back to the game selection. Am I missing anything?