Do you still have the original VM with a working Outlook database? If yes do not copy the .pst via the VMware Shared Folder feature and ensure Outlook is closed (no outlook.exe in task Manager not the the Outlook GUI not showing) and then copy it either via a USB Drive or mount the virtual hard disk in OS X and copy via Finder. VMware Shared Folder is fine for small files but I'd never use it on larger files, especially a 15 GB file! 
BTW You're only asking for trouble when allowing the Outlook.pst file to get to such a large size and regardless of what Microsoft say is an acceptable or supported size for the Outlook database I never allow my primary PST File to grow larger then 2 GB and maintain a set of PST Files to handle the entire Database. In other words I typically do not need to have more then the last year or two in the primary .pst and have many archive .pst that I can open as necessary or even keep a few open with the main .pst. Yes one might argue keeping it all in one .pst is easier however taking the easy way is not necessarily always the best approach!