InterBase Express (IBX) wasn't included in RAD Studio XE4, Delphi XE4 or C++Builder XE4 at release time but it is now available for download to all registered users of Delphi, C++Builder and RAD Studio XE4 and All-Access customers. IBX is not available for users of Delphi Starter or C++Builder Starter editions.
Download InterBase Express now at: http://cc.embarcadero.com/item/29408.
The download includes a readme file with install instructions.
You can learn more about InterBase Express in the RAD Studio doc wiki.