You only need to use Call Script if you use modus 3. Read the script:
# ---------------------------OPTIONEN-------------------------
# Modus 1 = Name of the map as: "mapname.png"
# Vb: "Dungeon.png"
# Modus 2 = Id as the name as "mapID.png"
# Vb: "1.png"
# Modus 3 = $name_minim[MapID] = "Screen" / screenone ".png"
# in Modus 3 you save all the images in /pictures/MiniMaps and asign them to the map with call script
#============================================================
@modus = 3
As you see, it tellse you the code that is necessary right there, though to be honest I am not sure what that / screenone thing is. If I were using this script, I would use modus 2. that way all you need to do is save all the maps as pngs with their name being the IDs of them. Remember, this is in a folder called Minimaps, located within the Pictures folders. You have to create that folder if you have not already. I think modus 3 is the least convenient method. So I suggest changing that to 2 or 1 and following the directions for them.