Full step by step guide for installing and enabling widgets:
1.Search your Zero-K installer folder (easy to do by opening local files with Steam) and create "Widgets" folder in Zero-K\LuaUI without the "s.
2.Install your widgets there as .lua files.
3.Next open the game and start a single player skirmish.
4.Open the ingame menu with Esc and toggle off "simple settings" on the bottom right corner of the ingame menu.
5.Navigate to Settings -> Misc and toggle on "Show Advanced Settings" This should make "Local Widget Config" appear, open it and toggle on "Enable local widgets".
6.The next time you play all your custom widgets should be shown on the Widget list under "User Local".