Problem with CSS content for some players on my server.

Hello,

I have a server in gmod, and one of my players spoked to me today, and said there was a problem with the css content.
The player there spoked to me, don’t have css on his steam account, but he have all the files from a CSS content pack and installed them,
so he has no texture fails/errors ingame.

The problem is that my server is spamming his chat with “You don’t have css, you have to buy it” - Something like that.
He has all the css files like if you have css over steam, but his chat getting spammed by this message.

How can I fix this?

This is probably a DarkRP message; ask on their forums.