The current Cinegy Archive functionality does not support such workflow.

However, you can use the Cinegy File Service which has the functionality of logging events when low free space is reached (e.g., 20%).

This message is recorded in the System event logs, but you might create a scheduled PowerShell script to look for a "low free space" event in this log and send a notification. Something like this: Get-EventLog -LogName Application -Message *low free space*.

This method is explained here: https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.management/get-eventlog?view=powershell-5.1