The 1.8 installer is roughly 15 megabytes.
The installed Renoise program directory, including demo songs, is roughly 25 megabytes
In other words, there isn’t one, but there are several demo songs which you can examine and borrow samples from to get started. You can also download the entries from the BeatBattle 5 compo, all of them are open Renoise songs just waiting to be played with. Not to mention BeatBattle 4, 3, 2 and 1.
No sound banks, no samples, no built-in synthesizers.
Before you even think of buying any VSTi synths there are tons of free ones available that are more than good enough, you can search the database at KVR Audio for a start.
Samples can also be found online for free if you look around.
Heck, there are tons of free VSTi instruments, among them is SFZ which is a free soundfont player… and also many free samples. Between all of them, and the amazing mutilating powers of Renoise, most anything is possible. Also just search for free loops, learn to use 09xx commands in Renoise and you will have a powerful tool indeed…