This is a reference to a for music producers, particularly in dubstep, electro-house, and bass music .
The "Zomboy Sample Pack" is from Zomboy (the artist) in the way that Vengeance or KSHMR packs are. Instead, it refers to a specific, legendary fan-compiled or leaked collection of sounds that allegedly came from Zomboy’s early projects (circa 2012–2015). Zomboy Sample Pack