I have installed RouterOS in Virtualbox on Mac Pro to test get a feel for the interface via Winbox but when I click on interfaces button and any of the interface fields they don’t have the Masterport option is this a limitation of the software or am I going about things wrong?

If you installed the RouterOS on a Mac Pro, then it is probably a hardware limitation. The ethernet ports on the Mac may not have switch capability, or at least not detected by the RouterOS.
Ok makes sense thanks