wanting to transfer files to a new Mac Pro from a windows pc using an external hard drive with a backed-up copy-key steps
how do I transfer backup from external hard drive to a Mac Pro?
Use the Migration Assistant app on your Mac to transfer data from a PC ..
The Migration Assistant is located in HD > Applications > Utilities
Migration Assistant copies all of your files to your new Mac so that you don't have to do it manually. If your files are currently on a Windows PC, follow the PC migration steps instead.
Move your content to a new Mac
Congrats on your new Mac!