Hello leta48,
Thank you for reaching out to Apple Support Communities, and we'll be happy to help in any way we can. We understand you're having issues with using the Auto-Reply feature. To start, follow the steps in this article to resolve the issue: Use the Driving Focus on your iPhone to concentrate on the road - Apple Support
"Turn on Auto-Reply
With Auto-Reply, favorites and those you allow notifications from will get an auto reply when you have the Driving Focus on. They can choose to notify you anyway by sending "urgent" as an additional message.
- Go to Settings > Focus, then tap Driving.
- Tap Auto-Reply.
- Select an option, like No One, Recents, Favorites, or All Contacts.
From here, you can customize the auto-reply message that people get when they message you while a Driving Focus is on."
We hope this helps.
Cheers!