Before you can use your Freecom external hard disk on your new iMac, you need to properly connect and set up the device in order to work on your computer. You can find a tutorial for this thing on the following official support website. After you did this, the hard disk should be available to use on your new computer. To be noticed that you probably won't be able to access all your data due to some compatibility issues between Windows and Mac OS, without any additional programs.
