What MAC OS versions does Poser 11 work on? Where is the Poser 11 Pro? What’s the difference between Version 11 and Version 11Pro? Especially important to me is whether the Cloth Room in Poser 11 (non-pro version) works with the Poser dynamic clothing I bought here, such as Older dynamic Clothes

I can't answer the questions about mac os versions. There is no longer a pro version. There is only version 11. When Bondware bought out Poser they chose to have only one version that included everything in the pro version. The cloth room should work with older dynamic clothing. I haven't found anything it didn't work with yet.

according to the manual Mac versions required is Mac OS X 10.15 or higher (64-bit OS required)

You can find the manual at the Poser website Menu > Support > Poser 12 Manual http://www.posersoftware.com/documentation/12/index.htm

direct link to the System Requirements: http://www.posersoftware.com/documentation/12/index.htm#t=Poser_Reference_Manual%2FIntroduction%2FWelcome%2FSystem_Requirements.htm

hope this information is helpful for you