Hello @ic_user4456,
Did you add the conf file for your Windows host yet?
Did you add the conf file for the service disk check yet? Since you installed the Icinga2 agent for Windows the disk-windows check command is included. You can setup a service using this check command. The best way to setup the check command is by setting up a apply rule where for variable OS=Windows. Add the OS=Windows variable to your template for you Windows conf files.
Don’t know if this will help you but on my side I installed a nrpe client on the windows server and wrote a few powershell scripts to check this kind of things (raid status, disk usage). Icinga will query then the server for this or that script and receive the answer from nrpe.
I wrote my own disk check scripts as it’s not logical for me to check the % filled of your disk. 5% free on a 40Tb volume is still 2Tb which is fine. I combine then the % free with the physical free space available and issue alerts based on that.