Quick answer:
make test.byte:
Have a look at the following topic for which set of packages worked for the first example:
https://discuss.ocaml.org/t/ocsigen-start-how-to-really-get-up-and-running-in-5-minutes/3066
sudo make run.byte:
You should do sudo make install.byte first, and also pass the environment variables of the normal user (because root has no opam environment).
Concerning the “Basic web site in OCaml”, let me have a look at my notes and come back to you.