I see during installation / upgrade from 2.18 rel. that the libwbxml library is required to the offline capabilities.
So i've installed related packages (libwbxml2-0, libwbxml2-dev and libwbxml2-utils), happy for this incoming feature.
But i'm not able to find where activate or enable that, so i presume it's a module.
i see in your home page site, in the key features section, the CRM item.
Maybe i misunderstand.