To add mods to a specific game, simply right click on the game in yuzu’s game list, select Open Mod Data Location. Extract the provided mods into this directory.
Note: At first I was extracting files from within the folder, do NOT do this. The Number "01006BB00C6F0000" below is for Zelda as an example.
"installdir/user/load/01006BB00C6F0000/ModNameA/" "installdir/user/load/01006BB00C6F0000/ModNameB/"
Confirm:
Right click game → Properties → "Add-Ons".
Sources for Mods: