Hi @blueman26 ,
This message appears when a specific user account lacks permissions to write/read files on the machine’s assets files location (in this case, C:\Users\USERNAME\Documents\V-Ray Material Library). Make sure you have, i.e., admin rights.
Alternatively, you can set a custom location for the assets library. Set the path in the ‘Asset Editor / Advanced Settings / Configuration / Remote Assets / Download Location’. SketchUp restart is required for the new location to be used.
Hi, I have the same problem with Revit '18 and I can’t find the similar solution. (I have admin rights)
Can you show a screenshot demonstrating the issue?
Have you tried setting another file path from the Asset Editor > Advanced Settings > Configuration > Remote Assets > D****ownload Location?
If you are still experiencing issues, best would be to get in touch with us through our contact form so we can schedule a remote session. Make sure to mention this thread in the email, thanks!
Dear radoslaw_ziejka, hello.
About the proper installation of V-Ray Material Library in Revit, please follow these steps:
1. Download the latest build from here.
2. Create a new folder in Documents named V-Ray Material Library and choose it in the Advanced mode of installation (visually shown).
If you are experiencing difficulties, please agree to connect in a remote session via TeamViewer.
It won’t take long and I will be able to solve the issue for you.
Wishing you a happy day.
Best regards,
TS
many thanks!! perfect 
Thank you for sharing.
Enjoy V-Ray!
