All USB based PowerLabs can be connected to and used with a computer's USB 3.0 port. The port will automatically revert to the USB standard being used by the particular PowerLab model.
Why does the PowerLab offer no USB 3.0 connection? USB 3.0 offers higher transfer rates and somewhat higher power for USB powered devices compared to USB 2.0. Since PowerLabs are self powered and the maximum data rate for a 16 channel PowerLab is well within the transfer rate provided by USB 2, there is no advantage going to USB 3 for that reason.