The mod works for both. If you can download it from the mod portal in-game, then it will work. It's actually not "only" for 0.18, the mod works for any version of Factorio from 0.18 and up.
If I change the mod version to 1.0, then it will stop working for those players who are still playing maps on 0.18 (though there shouldn't be many of those left).
EDIT: Skipped over 1.0, updated to 1.1
