Preface: you will need a http://bela.io preferably connected to WiFI.
sudo apt install luajit is necessary but not sufficient if you want to compile projects which #include <lua.hpp>.
Why? Because the default package does not provide a luajit.pc file for pkg-config to read and it can't find the headers.
So you need an install of LuaJIT which both targets armhf and comes with a luajit.pc.
According to Debian package search the only one that does is libluajit-5.1-dev (2.1.0~beta3+dfsg-5.1).
So what we actually need is:
sudo apt install luajit libluajit-5.1-dev