A MIDI sequencer just outputs MIDI instructions, it doesn't generate sound unless it implements a synth (sound generator) of some sort.
You'd need to install something like loopMIDI, and direct the output of the sequencer to the input of a VST host, where you can load whatever synths you want.
You'd need to install something like loopMIDI, and direct the output of the sequencer to the input of a VST host, where you can load whatever synths you want.