Modding FFXIV requires a few tools. Firstly it requires you use the XIVLauncher which injects Dalamud plugin API into your game. Secondly it requires that you set up Penumbra; here’s the official guide on that (has pictures too!).

There’s several other plugins that help with mods; the reniguide above covers these, but the most popular and important one is Mare Synchronos, which allows your friends to see mods from your game in theirs without having to do any manual file transfer or mod setup on their ends.

The website this post is about is a repository for paid mods to be made available freely, publicly; i.e. piracy. There’s several other free repositories for mods tho, the most popular of which are XIVModArchive, Heliosphere, and AetherLink.