Try these steps:
If none of the steps above help, factory reset your Chromecast and then retry setup. You may also want to try setup using a different phone or tablet, just to test, if you have one.
I appreciate your help here, davidking!
Sofiad, we hope that helps but, if you're still having trouble, please manually connect to the Chromecast SSID. Here's how: go to the phone settings > Open Wi-Fi and connect to the Chromecast SSID (Example: Chromecast1234, Living Room TV, Bedroom TV, etc.) > Go to the Google Home app and try to set it up again.
Just checking in to make sure that you've seen my response. Please let me know if you still need help or if you have other questions or concerns as I will be locking this in 24 hours. Feel free to start a new thread and we'll be happy to help.