Hi Allyson,
Hopefully your ATT router has DHCP server turned on which would give your AP's and Clients valid IP's for the router LAN interface.
You can verify this by plugging a PC into the ATT router and see if it gets a valid (private) IP - for windows you can check the IP from command prompt by running ipconfig command.
The AP's when plugged into the router also should get a valid IP in this range. The problem is determining what IP they get. Usually you can access the Router and check the lease table to see what IP was given to each device MAC address (found on the bottom of the AP).
While you could try to upgrade and configure the AP's after a factory default using the default IP of 192.168.0.1 it would be best to determine the IP assigned to the AP via your router so you can continue to access, configure and monitor them. You could set a static IP in the IP range used by your router.
If the WEB-UI is not working after factory default (it should) - you can try by accessing the AP via CLI/SSH and run the command - set https enable - this turns on the secure WEB-UI/GUI interface which is turned off if the AP is or was under control by a Ruckus controller.
I hope this helps.