Oh! The instruction got lost in the update!
If you are using Windows, unzip the archive and put the inner folder into your game world's Packs folder. To find that, navigate to C:\Users\[yourname]\AppData\Local\FoundryVTT\Data\worlds\[yourgame]\packs. You may need to have hidden folders visible to see parts of this path.IIf you are using something like Amp to host on a server, it's the same path, but starts at Data.
In your world, create a compendium with the Item type (as opposed to character or journal or whatever) that has the name of the folder, using a space instead of a dash. So power-effects becomes a compendium called Power Effects. It should auto-populate from the folder you dropped in; if it doesn't, reload the world.