In the first stage of that tutorial you don’t need to define active or passive since we are using instead random patches as restraints:
Step 4: Turn on random surface restraints. For this unfold the Distance restraints menu:
Define randomly ambiguous interaction restraints from accessible residues -> Check the box
You only need to define active and passive in the second stage.
So if the server complains about missing info, it means you did not follow all instructions in the tutorial.
As for defining the active residue for the ligand, simply give its residue number.