This issue is related to your iCloud configurations, looks like you have denied access to iCloud Drive or you don’t have an active iCloud account on your iMac.
Authenticator needs access to your iCloud account and iCloud Drive to restore, synchronize and back up your accounts. All your data are protected with strong encryption while in iCloud.
You can enable the iCloud Drive on your Mac by following these steps:
Select iCloud Drive.
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