Older .vismat or .vrmat files from V-Ray 3/4/5 will work but (e.g., no Clearcoat layer, broken translucency). Always prefer the V-Ray 6 optimized library inside Chaos Cosmos.
This is a firewall issue. The link requires access to https://resources.chaos.com . Allow your firewall to connect to Chaos Group servers, or use the offline installer link above. vray 6 material library link
V-Ray 5 New Material Library And Preset Materials for 3Ds Max no Clearcoat layer
: Use the "Materials" category to browse hundreds of high-quality, render-ready assets. One-Click Import vray 6 material library link
The is no longer a separate standalone download. Starting with V-Ray 6, the entire preset material library has been officially integrated into the Chaos Cosmos Browser . How to Access the V-Ray 6 Material Library