Defedner for Server licences for Server 2012 R2

We are pretty new to defender suit of products so struggling a bit, we are mid sized company below 300 employees who got Defender for business preview and now as its in GA our assumtpion is that, it will become part of our business premium subscritpion, the confusions for us is that what licences do we have to buy for our server 2012R2 servers to run defender AV and MDE, does this Defender for Business is enough or do we have to buy Defender for endpoint seperatley for serevrs, mind you I was able to onboard one server with any additional licneces so it would be complaince reasosn I guess, one more query if some one can assist, how can we centrally manage defender AV on server 2012 R2 serevrs, like applying polices across all servers etc, would this be done individualy as I can not enroll servers in intune, thanks in advance for any contribution to this discussion..