Version 1.4.4.9 is a common stable build for dedicated servers. You can download the specific server binaries directly from the official API: Dedicated Server v1.4.4.9
Buying Terraria on GOG has specific pros and cons compared to other storefronts: 1.4.4.9 - Official Terraria Wiki terraria 1449 gog
~350 MB Post-install: ~500 MB
GOG players can play with Steam players on version 1.4.4.9. However, you cannot use the Steam friend list to join. Version 1