The companion

The small app that carries the guild's sheets.

Download it on /account (Windows). Windows SmartScreen will warn about an unknown app: More info → Run anyway.
Leave it open while you play. It finds your WoW folder, posts sealed sheets, and every five minutes writes what the site knows into the addon's folder.
While it runs you are a collector: your game carries the sheets of guildies who have no companion.
Running it is a mission of Chapter II (The courier).

There is no Mac version yet.