Probably a beginner question but…
is it possible to use polar electrolytic capacitors for the logic power supply as well as the stepper power supply. The schematic in the introducing PDF-file shows some unipolar caps, so I’m a little bit confused due to my minor experiences.
Are you referring to the getting started guide from this thread?
The decoupling capacitors shown in that guide are not strictly necessary; the A4983/A4988 stepper driver carriers are designed to be usable as-is. However, it does not hurt to add additional decoupling, and you can use as big of a capacitor(s) as you want (more capacitance will provide more smoothing for the supply voltages).
It does not matter whether the capacitors are polarized or not; just make sure you connect them in the correct orientation (if they are polarized) and that they are rated for the voltage you are using them on.