@Handian Sudianto Thank you for reaching out to us, As I understand you are trying to onboard windows server 2012 R2 to Microsoft Defender for endpoint (if my understanding of the issue is incorrect), please let me know.
Request you to review the pre-reqs of onboarding the 2012 R2 server to MDE - https://learn.microsoft.com/en-us/microsoft-365/security/defender-endpoint/configure-server-endpoints?view=o365-worldwide
Same has been explained here as well on the steps - https://www.youtube.com/watch?v=8v2Or1ncySg
Let me know if you have any further questions, feel free to post back.
Please remember to "Accept Answer" if answer helped, so that others in the community facing similar issues can easily find the solution.