Computer? if Windows pi-star.local will not work -- try
http://pi-star/ if nothing else find the IP of the Pi-Star and use it instead.
If you are using a Cell the only way mine works is the IP as the Cell hotspot doesn't do nameserver stuff like a home network would.
If you see pi-star-setup in the list of networks and connet to that on your computer, then you should use
http://192.168.50.1/ as the place to go to set up the wifi of your home/work/cell, whatever. I don't think I've ever had pi-star work on initial setup, always 192.168.50.1
You may get a No Modem Defined when you do this, it is normal, just config for your radio board, apply changes, (you may have to do twice, sometimes mine did that. Then scroll to very bottom of configuration page (if you didn't already get the Username and password, they are pi-star and raspberry respectively.
Once you enter the first WIFI network (Save and connect), I find mine don't actually work until [Apply Changes also] and Reboot the Pi-Star so it connects to your 'real' network. Then pi-Star (or whatever the HOSTNAME is (pistar) I think at one time they took out the dash in the middle) should work fine.
Good Luck.