Thanks for reaching out. Please try the steps below and let me know how it goes:
Adjust the settings of the setup device. For Android, please turn on location services. For iOS devices, turn on Bluetooth and Local Network Access.
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 up again.
Force close and reopen the Google Home app.
Uninstall and reinstall the Google Home app.
Try to use another supported device.
Reboot your router.
Reboot your TV.
Reboot your mobile phone.
Reset your TV. If you're not familiar with this, please reach out to your TV manufacturer for additional help.
Just checking in to make sure that you've seen my response. Please let me know if you have other questions or concerns as I will be locking this in 24 hours if I won't hear back from you again. Feel free to start a new thread and we'll be happy to help.