1. From the game panel > config files, edit the DefaultGame.ini file and make sure you got the following setting under [AAGame.AAGameMultiplayerBase] :
bServerSteamUGCAutoUpdate=true
if it is set to false, change it to true and save your changes.
2. Now go back to the game panel > config files and edit the AASteamUGCManager.ini file.
Under [SteamUGCManager.SteamUGCManager] you can add your steam workshop contents to add as follows:
ServerSubscribedItems=(IdString=STEAM_WORKSHOP_ID)
So for example:
ServerSubscribedItems=(IdString=540019282)
Note that the steam workshop ID of an item is the numeric part at the end of the url (web link) of the item in the workshop. In our exemple the workshop item url is https://steamcommunity.com/sharedfiles/filedetails/?id=540019282 so its steam workshop id is 540019282
You can add multiple lines (one per ID); for example you would then get:
[SteamUGCManager.SteamUGCManager]
ServerSubscribedItems=(IdString=540019282)
ServerSubscribedItems=(IdString=730525924)
ServerSubscribedItems=(IdString=320694949)
Save your changes and restart server. The workshop items should then start downloading (you can check that in thegame server log ). You should then see your items downloaded into the following folder:
/Binaries/Win32/steamapps/workshop/content/203290/
You can now add your maps to the map rotation or the map vote list editing the DefaultGame.ini file from the game panel > config files.
Note that you MUST use the correct map name. If you don't know the map name simply go into its folder, for example /Binaries/Win32/steamapps/workshop/content/203290/320694949
You will see a *.umap file, the map name is the part just before the .umap extension, in this case we got FLO_Pipeline$76561198032909027_ac.umap so the map name is FLO_Pipeline$76561198032909027_ac
ATTENTION:
Do not use more than 20 maps in the MapVoteList or your server might bug out.
ALSO you can only have 3 custom maps listed in the MapVoteList section.
Do not use more than 39 lines of code in the MapRotationList and MapVoteList section or your server might bug out.