There should be no problem with opening the project. What error message are you seeing that tells you it won't open?
What version of CS6 is running on each machine?
There may be a problem with the project file. Try this trick: make a new project file on the Mac, and IMPORT the windows project file into it. See if it helps.
Whatever issues you have have nothing to do with Mac vs. PC. It's more likely you either introduce a security/ file permissions problem when transferring the file, it has an invalid special character in teh file name or it references some external file that may be required.