Salamun Market is only available in Warzone matches. You can set Salamun Market as your preferred map for Warzone in the Main Multiplayer menu. The Tactician is the only class that can capture Tactical Spawn Areas. When your faction manages to accomplish the feat of capturing all four Tactical Spawn Areas in Salamun Market, meaning whenever you control all 4 points at any time, the trophy will unlock. You don't have to capture them personally, just as long as your team controls all 4 areas.