I’m Presuming from what I read it’s an inverter driving a 3 phase motor off a single phase supply, I did the same with my Meddings pillar drill, it works well but you can lose torque at low speeds, bought my inverter & station from Transwave.
There isn't a catch as I understand. The appear to be selling a variable frequency drive with a three phase motor and a 3 step pulley to get torque throughout the speed ranges you'll need. The Variable Frequency Drive (VFD) electronically converts single phase power into three phase with the ability to vary the hertz/cycle to adjust the speed. They have packaged it up for you so you don't have to source a VFD, motor, hardware, wire it up and program the VFD.
Hmmm. Ok - I was thrown by the bit that says "Both run on a standard domestic 240 volt single phase supply. Three phase versions are also available" - which seemed to imply the former was a single phase system.