to build, run
make
(tested on Ubuntu 20.04L)
Note that it will try to check out https://github.com/acoli-repo/postil-time-machine into src/postil-time-machine. You might want to do that manually (or, create src/postil-time-machine as a symlink to an existing repo folder).
resulting website should be under https://acoli-repo.github.io/postils-website/
At the moment, it doesn't get the CSSes and this slows down page display.