Hi,
Easiest to achieve this is to create a PowerShell script that checks the disk space of your disks, then schedule the PowerShell script with the Task Scheduler to automatically run the script and notify whoever you want about low disk space.
There are many guides out there that provide solutions for this, here's a few examples:
PowerShell: Alert me when Disk Space is running low on my Windows Servers (E-Mail Notification)
PowerShell : Monitoring and Notification - Disk Space Alerts
Automated Disk Space Alerts For Windows Server
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Best regards,
Leon