You should be able to completely set up the device without network access. Then you can set up that after the device if fully running. If it won't set up without the network access, then that is really odd and I would contact the manufacturer.
NOTE: If none of the following work to resolve the problem, and if the tablet is under warranty, I would contact the manufacturer.
1. Try and restart the tablet. Sometimes it is that simple.
2. Update the firmware and any apps that need updating on the tablet.
3. If the problem persists, check your time and date on the tablet to make sure it is correct.
4. Should none of the former work...
a. Clear out the WiFi data on the tablet.
b. Reboot the modem/router.
c. Once the modem/router is fully...