note: this is using the EA app since origin is not available on PC anymore
If I remember correctly, there's some confusion in the exact names of the folders made by the game in different places; specifically, in whether the first part of the folder name is supposed to be "Command and Conquer" or "Command & Conquer". It's possible that the game installation process on Origin/EA App creates them incorrectly. So if you do find the folder but it doesn't work, try renaming that and see if it makes a difference.
Also note, each map needs its own folder inside the maps folder.
Besides all that, though... as several of the guides you linked to specifically say, if there's no "Maps" folder in these locations... just create it yourself.
