Seems like you were bit by autotools. Your screenshot shows clearly that the engine can not find the game data (namely, conchars.tga). Either you didn't download the data via rsync, or it's not where Quake2World expects it to be.
The expected layout is as follows:
$prefix/bin/quake2world
$prefix/lib/default/game.so
$prefix/share/quake2world <-- game data lives here
Perhaps you forgot --datadir? Why not just use --prefix instead? Better yet, why not just use the defaults?
Anyway, the above information should have you on your way.
The directory structure I described above is how GNU/Linux packages are typically installed. Q2W is very normal in this regard. On Windows, the Update.bat script creates the correct structure for that platform.
In short, use the defaults and don't worry about it :)