kali linux setoolkit problem (HELP)

Hello, I've been trying to use the setoolkit I downloaded kalilinux from virtual box onto my mac everything seemed fine but once I tried testing the cloned website all that came up was "This site can't be reached" why is that? I looked online for steps and I came across that screenshot but how did they find the the number "/24" after the netdiscover-r192.168.243.0
help would be much appreciated!
Attached Thumbnails