@EnterpriseArchitect Thank you for reaching out to us, Defender for identity needs these pre-reqs - https://learn.microsoft.com/en-us/defender-for-identity/deploy/prerequisites as per the licensing requirements mentioned in this and licenses which you (as mentioned in the query does meet).
Review the other pre-reqs like permissions, connectivity requirements and recommendation for proper deployment of defender for identity within your environment.
Also review below mentioned docs for reference:
https://learn.microsoft.com/en-us/defender-for-identity/deploy/capacity-planning
https://learn.microsoft.com/en-us/defender-for-identity/deploy/install-sensor
Let me know if you have 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.