You didnt setup your sever correctly. As I said on my profile,

you need to setup your server to tell clients to download the resources. Make script with either individual lines with resource.Add for each model file or with resource.AddWorkshop("657241323").

For WS pack, either resource.Add every single file or create MOTD telling ppl to download content from git before joining.

Error you described on my profile indicates you installed addon on server, but not on your client.