- Stop server.
- Install map mod as per https://pingperfect.com/index.php/knowledgebase/95/Conan-Exiles--How-to-Add-Mods.html
- Click "Commandline Manager"
- Click "Select" / "Selected" next to the 'Custom' commandline
- For the 'Map' value, specify
/Game/Mods/Savage_Wilds/Savage_Wilds
ReplaceSavage_Wilds/Savage_Wilds
with the file name of the map you are using if it's not Savage Wilds (https://steamcommunity.com/sharedfiles/filedetails/?id=2377569193) - Startup server, enjoy.