Description:

PrBoom+ is an enhanced DOOM engine developed from PrBoom.
The target of the PrBoom+ project is to extend the original port
with features that are necessary or useful to the developers and all
those interested in their work. It is worth noting that all changes
introduced in no way break PrBoom's compatibility with the original
DOOM/DOOM2 engines.

PrBoom+ does not include any levels itself. More importantly, you need
all the sounds, sprites, and other graphics that make up the DOOM
environment.
So to play PrBoom+, you need one of the main DOOM date files from id
Software: either doom.wad, doom2.wad, tnt.wad or plutonia.wad from one
of the commercial DOOM games, or install FreeDOOM.