Samizdat is supposed to be installed by the superuser on a VPS or on bare metal. If you prefer easy installation and smooth software upgrades, go with the Ubuntu preparation. If speed and fine tuning is what you desire, plus you're a skilled sysop, go with the FreeBSD ports setup.
Samizdat offloads serving of static content to Nginx. An other way they work together is by sharing cookies through Redis. Some small Lua code in Nginx then helps authorization.