Problems with X-Com-Files install.

[danyll]

While attempting to install X-Com-files mod for UFO defense, I get an error while launching the game.

ERROR: failed to load 'UFO: Enemy Unknown / X-Com: UFO Defense' ; mod disabled for next startup
GEODATA/WORLD.DAT not found.

[BlackStaff]

https://openxcom.org/downloads-milestones/
   OpenXcom requires a vanilla version of the original UFO: Enemy Unknown / X-COM: UFO Defense (any edition) with the latest patch. It is not compatible with other games in the X-COM series. If you don’t own a copy, you can buy it from one of these retailers.

Do not use modded versions of X-COM, as they may be incompatible with OpenXcom.
https://www.ufopaedia.org/index.php?title=Installing_(OpenXcom)

[Solarius Scorch]

Well, first of all, X-Com Files runs on OXCE, not vanilla OXC...
Perhaps it's obvious, but I don't know what the problem is.