Installation

What is in a download, where to put it, and the prerequisite people miss.

A download contains the engine binaries for the platforms that package covers, the binding for its language, the examples, and a readme. Unzip it somewhere your build can see and point your project at it.

What differs by package

Native packages: A shared library plus a header or an import library. Link or load it the way you would any other native dependency.
Managed packages: Source files that call the engine directly, plus the native binaries. There is no separate runtime to install.
Script packages: A binding module plus the natives for the platforms that package ships. The bitness of the native must match the interpreter.

The per-package prerequisites -- which runtime versions are supported, which platforms are excluded and why -- are listed on each package's own page, generated from the same source the engine is built from, so they cannot drift from what the download actually contains.