Run the game via steam and see if it will update.
The mod works on the current version of the game.
It is also possible that you have a file in its folder that is unwanted by mod, eg a localization file, folder set to "read only" If the mod is unable to replace files in its folder, the update will not be successful.
Check internet connection.
It works for others, it
works for me, so it should be for you too.