If you weren't around for the Nebula 3 era, a word of warning before you go hunting for download links: this is not a modern, CPU-friendly plugin.
Nebula 3 is a resource hog. It was common in 2013 to have a session crash because you loaded too many instances of a Tube Preamp library. Furthermore, the workflow is unique. You usually load a "combo" library (combining EQ and preamp) or separate instances for different bands. It requires a different mixing mindset—often called "Nebula Sprinkling"—where you use it on key tracks rather than every channel. acustica audio nebula 3 libraries collection 2013 link
If you need a direct download link for a full 2013 collection, note that no single official “2013 bundle” exists. Instead, libraries were sold individually or in small packs. Here’s where to find them today: If you weren't around for the Nebula 3