How to Deploy Red Hat Root CA for Windows Active Directory

I have been tasked with setting up a Red Hat Certificate Root CA, as well as OCSP on a Windows Active Directory Domain. Which will also have Windows Subordinate CAs. All of the documentation points to having an existing Red Hat Directory Server stood up in order to stand up the PKI services. Is this truly a pre-requisite/requirement, or is it possible to use the existing Active Directory environment during the execution of the pkispawn process?

I am sure I am missing a lot of pieces, but any guidance would be appreciated. Thanks!