If you are using macOS Mojave or Catalina, you'll need to give iBackup Extractor permissions to be able to view your iPhone backups. Here's how:
https://www.wideanglesoftware.com/support/ibackupextractor/view-iphone-backup-on-mac.php
If your Mac is running an earlier version of macOS, the extra permissions are not required. If this is you, follow the guide below to find out how to access your iPhone backups:
https://www.wideanglesoftware.com/support/ibackupextractor/view-iphone-backup-files.php