Replacing MyProject and <your_appid> with the appropriate values, something like:
public class MyProjectServerTarget : TargetRules
{
public MyProjectServerTarget(TargetInfo Target) : base(Target)
{
Type = TargetType.Server;
DefaultBuildSettings = BuildSettingsVersion.V4;
IncludeOrderVersion = EngineIncludeOrderVersion.Unreal5_3;
ExtraModuleNames.Add("MyProject");
GlobalDefinitions.Add("UE_PROJECT_STEAMPRODUCTNAME=\"<your_appid>\"");
GlobalDefinitions.Add("UE_PROJECT_STEAMGAMEDIR=\"MyProject\"");
GlobalDefinitions.Add("UE_PROJECT_STEAMGAMEDESC=\"My Project\"");
GlobalDefinitions.Add("UE_PROJECT_STEAMSHIPPINGID=\"<your_appid>\"");
}
}