This code is in early stages of development and contains more bugs than features. Do not expect it to be compatible with normal documents. Also later versions will contain many breaking changes.
You need an up-to-date TeX Live installation.
Currently LuaMetaLaTeX uses a patched version of LuaMetaTeX for which the source can be found at https://github.com/zauguin/luametatex and a support C library for which sources can be found at https://git.math.hamburg/marcel/luametalatex-c. I recommend using prebuild binaries, but you can also build them yourself and then use them instead of using the installer in the installation instructions.
l3build install in this directory to install the Lua files.installer. If your current user does not have permission to write into the binary directory of your TeX Live installation (this is typically the case if you have a multi user installation) then you need to run the installer with administrator rights and pass the absolute path of this directory to the installer.