quick note: My Google Home mobile App also spits out “Couldn’t update the setting. Check your connection.” sometimes after I authorize GH on myopenhab.org.
Even with this message, the devices will still show up in the GH App. I have done the setup more than 10 times because I was writing a tutorial and I was testing it extensively.
Check the FAQ here: HowTo: Listen & Talk to your Home
In general: If your cloud connector is set to remote+notify, you Items have been exposed, have received 1 update and as a result: can be displayed on openHAB Cloud - Log in and have proper labels and tags… they will show up in GH App.