The subwoofer has its own inbuilt power unit - you can plug it directly into mains electricity. So if you do that and plug it to your Mac it will work - as a subwoofer. As I say, I can't predict whether if you connect a couple of ordinary speakers to it they will work. In order for that to happen it would have to contain amplifiers for those speakers.
My guess it that it won't work. I suspect you are intended to connect an amplifier's speaker output to the high-level input on the subwoofer, and then it will pass the signal on to ordinary speakers while providing its own low-frequency output. As do many of these devices it provide alternative inputs - what I've just described for an ordinary stereo set up, with the line level input for home cinema receivers which have a dedicated subwoofer output (5.1 cinema soundtracks have a subwoofer track and output which contains only the very low frequencies, so that for example the bass component of explosions isn't sent to the main speakers but only to the subwoofer).
I should connect it up and give it a try. You won't do any harm (though make sure you start with very quiet sounds so as not to risk damage to the other speakers, and don't plug the audio leads in and out when the system is powered). The worst case is that you simply won't get any sound out of the other speakers.