Usually you’re bringing an unlocked iPhone near. If you have an iPhone, use that.
To be clear, you’re not ever using the Home App to set up the Apple TV as a Hub.
You do this in Apple tv settings as instructed above.
You’re going to sign into iCloud with your primary Apple ID - go over to the Airplay & Homekit setting to finalize it by choosing a room.
After all this, the Apple TV will show up in the Home App and it’s now a Hub.
Just be sure to use the same Apple ID across all devices.
Update all software first, apple tv, iPhone & iPad.
Make sure keychain and Bluetooth is enabled on your iPhone & iPad
its best if everything is on the same home wifi network. Make sure you have internet on your Apple TV and other devices, check airplane mode or low power mode isn’t on with your iPhone.
Reboot the wifi for good measure.
Try it again .
To start, first sign out of iCloud in Apple TV settings, restart (not reset) Apple TV, then sign back into iCloud
Then proceed as instructed above - perhaps restart your iPhone first before it asks for you to bring it near - you can ask Siri “restart my iPhone” if that’s easier