All plugin parameters can be controlled from the host application via automation.
The plugin follows tempo and playback position and state of the host application.
The plugin records and plays only when the host application playback is enabled.
AU version of the plugin is a MIDI FX plugin.
In Logic Pro X you can find the plugin from MIDI FX/Audio Units/Repeto.
VSTi version does not generate any audio, it has a dummy stereo audio output which always generates silence.
In order to hear and record any MIDI, the plugin must be placed on a MIDI instrument channel in the host application and the MIDI output from the instrument channel must be routed to a MIDI instrument (virtual or external).