Unzip the download, and place the .pck file in the game's mod folder.
Full instructions on where to place the pck file is available on the cassette beasts wiki.
If you wish to build the mod from source, the source files are included in the download. You will need to copy the folder inside the src folder to the mods folder in your development setup. You can then export the mod from godot using the instructions from the developer wiki.
