MS Defender for Endpoint for Windows Server OS

[JamesGordon11]

Hello,
we have a small environment consisting of 1 Windows client and 2 Windows servers and would like to license MDE EDR for all those.
I've read that you cannot use the same license for the server OS as for the client OS (MS Defender for Endpoint P2) and instead need to enable MDE on servers via some Defender for Cloud license?

Also, the following page mentioned something about having a minimum of 50 licenses already purchased before this is possible: https://learn.microsoft.com/en-us/microsoft-365/security/defender-endpoint/onboard-windows-server?vi... 
However, this page was updated just yesterday and now I'm not sure anymore what to do...

Question:

To have MDE with EDR functionality enabled and licensed on 1 client and 2 servers, what licenses do we exactly need to buy?

Thank you very much for any help!

[#2]

I am not sure if you need to have minimum buy of 50 licenses windows defender plan can be brought for those server I guess it costs around ~$15 per licenses https://learn.microsoft.com/en-us/azure/defender-for-cloud/defender-for-cloud-introduction

[#3]

Can I enable this also for selected servers or only for a complete subscription where all servers within the subscription are billed?

[#4]

you can enable for selected server only