Cannot find dll file in Unity folder (Mac)

I’m trying to use SQL inside my game for storing data that 2 device can refer to. However, when I tried to include “using System.Data” it didn’t give me the option. I found out that I need to add System.Data.dll to my assets, but unfortunately I can’t seem to find it. According to the post I’ve found, the file is suppose to be at


But I can’t see any folder called Did I misunderstood something here? There is an Unity application file inside the Unity folder, but how do I treat that as a folder (if that’s what I’m suppose to do)?

On OS X the extension .app is used as you know to identify executable applications, but it’s really a folder (if you try to copy it on a Windows system you’ll see it) and you need to right-click on the file then click on “Show content” to see the folder tree.