Apple includes the Ink Handwriting Recognition capability in OS X El Capitan, as it has done for prior OS X releases for years. This capability is only available when a graphic tablet is connected, and the tablet has supporting software compatible with the current release of OS X. When this is the case, the Ink preference pane will be available in System Preferences.
Ink will allow you to write or print freehand into either Pages itself (have not tested this with Pages v5.6, or v5.5.3), or its own software tablet. The linked article is from summer 2014, and likely deals with Pages v5.2.2 and Mavericks.