@Aran Billen, Thanks for posting in Q&A. Please check if the windows server is with support version and if the required KB is already installed which mentioned in the following link:
https://learn.microsoft.com/en-us/mem/intune/protect/mde-security-integration#supported-platforms
Check if the device exists in Microsoft Entra and we can assign security policy to the device group.
Hope the above information can help.
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