Add it to your server
In your server's .ini file (servertest.ini by default), add these to the existing WorkshopItems= and Mods= lines, separated by a semicolon (;).
WorkshopItems=3815685972;3826040163
Mods=ProjectRPG;ProjectRPG_ExpandedTree
These lines include the mod it requires, as its Steam page declares it:
- Project RPG ·
ProjectRPG
| Workshop item | Subscribers | Declared in |
|---|---|---|
| Project RPG: Expanded Tree (addon)3826040163 | 14 | description footer |