When you download the file at the bottom of update posts, the file needs to be dragged into your mod folder. This can be found by opening your game, going to the mod repository, click on "Mods" tab on the top left and click on the button that says "Open Mods folder." The file gets dragged over to this folder and should look just like the part I have underlined. Don't unzip the file.
Make sure you uninstall the previous version you had installed. If you had it on the online repository, you need to go and delete that version ingame, otherwise you will have 2 versions which can cause problems.
If you're updating from a previous file in the mod folder, just replace/delete that one.