Hello Mike-
Thanks for the question, I’m sorry to hear that you’re not able to create backups as expected.
This is a pretty strange error- creating a backup uses the same database credentials that your overall WordPress website uses, meaning that if your website is working at all then you shouldn’t see that error.
The first possibility that comes to mind is that your web host may have disabled Database Exports for your MySQL user. You can test that possibility if you have command-line access, by running the command:
mysqldump -u {Your MySQL Username} -p {Your MySQL Password} export.sql
You can get the username and password from your wp-config.php file. You can also try this command if your host includes WP-CLI on your server:
wp db export
If these commands don’t work, I’d recommend contacting your web host to see if your database user has the correct permissions to export the database.
I hope this helps!