How much space do the sliding track system need?

This depends on what series you are using and whether multiple parallel tracks are used, for instance. As a rule of thumb regarding width is that the sliding track should be two times the width of the door.

With regard to depth, the track system of a sliding door typically takes this much space:

Interior sliding doors: approx. 40–80 mm.
Storage and industrial sliding doors: approx. 50–115 mm.