That's correct it isn't support on Server 2012 (non R2)
https://learn.microsoft.com/en-us/windows/security/threat-protection/microsoft-defender-atp/tvm-supported-os
You may get it to install but in the end you'll have an unsupportable system. If down the road you needed to call microsoft for support the first thing they're going to want to do is get it to a stable supported condition. A better option may be to upgrade the operating system.
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