When does that error happen?
Is this addon known to cause conflicts? And what does DLIB do?

We get this error the moment we load into the server. DLIB (https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1153306104) is necessary for DPP to work (https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=659044893).
This is the first problem we've had with DLIB

Should be fixed with this update, thanks for reporting:

Fixed an addon conflict with DLIB causing this error:
- lua/streamradio_core/client/cl_lib.lua:124: attempt to call field 'GetControlKey' (a nil value)

Fixed clientside files not loading for some clients.
Removed the community playlist for Mushroom Kingdom as it is down.

Thanks!

This is related to: https://steamhost.cn/steamcommunity_com/workshop/filedetails/discussion/246756300/1693785669860629663/

This error was caused by the addon not being loaded on the client, because the server also didn't load the addon.

I can't seem to figure out why it isn't working

Please also do the stuff I told the other guy in the thread I linked above. The error is because the server couldn't send the stuff to the clients, so you need to check for server side errors in the server console and tell me them. More information why that happens is in the other thread.

Thanks, I have found your problem:
3D Stream Radio (rev. 365):
Your GMod-Server (Version: 170422) is too old! Update your GMod-Server! Load aborted!

However, I don't think your server is THAT outdated because you can still connect to it.
I never seen this problem before, but maybe this would help:

1.) Delete <server>/garrysmod/garrysmod.ver (this file seems to have the version number in it)
2.) Start steamcmd and login as anonymous
3.) Run this: app_update 4020 -beta NONE validate
4.) Check <server>/garrysmod/garrysmod.ver to be at least version 171212
5.) Restart the server, everything should be fine.

I guess from the log that the <server> path would be:
"/home/tcagame_svc15092/IsraelT/15092/"

That worked, thanks!

No Problem, as it is fixed now, I will close this.