Creator Overlays is available under the MIT license
To install, you'll first have to install the Fabric Mod Loader. Once Fabric Mod Loader is installed, all you have to do is put the Creator Overlays .jar file and the Fabric API .jar file into your mods folder.
For instructions on how to use, visit the Creator Overlays wiki at: https://github.com/fragger57/creator_overlays/wiki