They work on Layers RRO theme engine, so you must have a ROM that supports it (stock Marshmallow does). Like in all Layers themes, root is ALWAYS needed to install the overlays, and you should install BusyBox too.
Our intent is to make more and more mods easily install able and removable, without the need of reinstall the whole system if you want to remove them.
You need to install Ambient System UI plus Ambient Framework. If your ROM does have ambient display functionality, don’t use the ambient display overlays. They would be useless and could cause issues.
If you exceed this limit by using a theme, for example,part of the overlays will not have effect or will cause boot loop. (if this happens, you can delete some overlays with recovery’s file manager. The overlays are located in /system/vendor/overlay/ ).
Layers Toolkit RRO Layers v3.0.9 Android