The Subscribe button on this page can be used to start the download process. The mod should then be available in your game Mods when you next launch the game.

If it helps we also have steps to download mods on our Support page: https://www.ageofempires.com/support/aoe2/#dl-mod

Wondering the same - I'm subscribed, it says it's installed here, but doesn't show up in game "installed mods" menu