It seems the archived version from "open-tibia.com" doesn't work. But I found the Sourceforge repository from 2005 here:
An open and free Tibia MMORPG server and programs to control it.
sourceforge.net
It's in the "
Survival Server 0.5.67 + SurvivalControl (SOURCES)" folder. I'll attach a copy of it here.
I haven't tried it and I have no idea if it's the latest version of their sources, but it says it's for Tibia 7.1
It also includes sources for the 7.4 version.