That's because the instructions are outdated.
Assuming you've installed Lotatc v3, if you check inside your .\LockOn Flaming Cliffs 2\Config\Export, you'll find the file that has to be taken into account inside export.lua, is named as "lotatc2_2-0.lua".
So, the appropriate syntax of the line you need to put into export.lua, has to be the following:
dofile("./Config/export/lotatc2_2-0.lua")
It was all about an undocumented filename change ;)