By hand
- Find the mod on the ARK: Survival Evolved Workshop and note the number after ?id= in its link.
- Download it with SteamCMD: +login anonymous +workshop_download_item 346110 <id>
- Unpack it into ShooterGame/Content/Mods/<id>: every .z file is compressed and the server needs the <id>.mod file built from mod.info. Tools like arkmanager do this; on Windows the game's Steam client does.
- Add the ID to ActiveMods= in GameUserSettings.ini, comma separated, no spaces.
Load order
ActiveMods is also the priority order, and the FIRST listed wins: "Priority is in descending order (the left-most ModID has the highest priority)" (ark.wiki.gg). A mod that overrides another, such as a patch for it, goes before it.
Crossplay and mods
Epic Games Store players cannot use mods. A server with crossplay on should stay vanilla, or its Epic players cannot join.
On a Flux server
The Mods tab takes a Workshop ID, a link or a whole collection, shows each mod's title and size, lets you reorder them (top = highest priority), and tells you once each is installed. The server downloads and unpacks them itself on its next start, and checks the Workshop for updates every 30 minutes, warning players before it restarts onto one. Removing a mod removes what it added to the world, so the tab asks first; the backups can roll it back.
Frequently asked questions
Do players need to install the server's mods?
No manual step: when they join, the game downloads the server's mods first.
Can a Linux ARK server run mods?
Yes, once they are unpacked. The Windows build of each mod is the one servers use, on Linux too.