Steve,
perhaps your referring to the reason that RTMM Library 'AhZx_LIB SUB LibraryFSXP3D' does not say OZx. That name triggers certain file modifications when using the FTX Central V2 which would also modify files in our library if the name was the same. Other than that I don't recall any 'caveat'. As long as the RTMM name is as quoted above you should not have any problems.
If this is NOT the case I'm sure one of our library experts will jump in with other instructions.
EDITI just found this in the Object Library Page that may apply to your question:
NOTAM for those who also have OZx Sceneries installed including the OZx_LIB:
a. RTMM no longer requires OZx Libraries but if you use them for OZx Scenery that is fine.
b. FSX users: If you see the Land Rover and Phone/Post Booth but do not see the green shipping container, you may not have disabled a portion of the OZx_LIB as instructed in the AhZx_LIB SUB LibraryFSXP3D installation instructions and/or you may not have the AhZx_LIB SUB LibraryFSXP3D enabled in your scenery library.
c. Prepar3D users: If you see the green shipping container but do not see the Land Rover or Phone/Post Booth you may not have disabled a portion of the OZx_LIB as instructed in the AhZx_LIB SUB LibraryFSXP3D installation instructions.