Sorry for the late response.
Thanks, icekohl.
Everything is working fine now. I just think that it's a bit weird that it cannot download the game files. We've tried on 3 different servers now. It still gave me an error after I used my own account. When downloading all of the files through SteamCMD manually and placing them in /home/tcadmin/tcafiles/games/kf-linux, it worked fine. Updating the server went fine as well, but if I delete the content of /home/tcadmin/tcafiles/games/kf-linux, it gives me the same error. However, I somehow got it working (I just tried doing the steps again), and then I tried deleting the content of kf-linux, and guess what... Now it doesn't work anymore... Whenever I try making a new server, it says Error: The file /home/tcagame/Dennis/169/System/ucc-bin does not exist
The file is found ind the /home/tcadmin/tcafiles/games/kf-linux directory, but is apparently not being copied to the new game server. Anyone got a clue?
Edit: Deleted the contents once again, and now it works again... This is the weirdest thing ever lol.
Another thing; I'm using my own Steam Account for the download and update, as the game cannot be downloaded without a subscription. Whenever someone updates or a new game server is downloaded, I get thrown off of Steam. Is there a way to fix that?