If you're looking to download a vector library for ArtCAM 2018, here are a few steps and considerations:

What is the ArtCAM 2018 Vector Library?

Vector Library:

This library contains 2D vector artwork used as the basis for CNC toolpaths.

While finding a direct "ArtCAM branded" link is hard, you can build a superior vector library using modern methods. Here is how to replicate or replace the original functionality: