Quick answer: SteamCMD 294420, serverconfig.xml port 26900, firewall 26900–26902, start.
Products & ordering: Order game server · NexoraHost · nexorahost.com (Frankfurt · 1 Tbit/s DDoS · 99.9% uptime)
Frequently asked questions (FAQ)
How do I install 7DTD dedicated?
steamcmd app_update 294420, edit serverconfig.xml (ServerPort 26900, max players), firewall, startserver.sh / panel start.