If you want to connect your WD external hard drive to Mac and Windows computers, you have to format the external drive with the FAT32 file system. In Windows, you can format up to 1TB drive through Command Prompt. There are various types of WD external hard drives. If you are using a Mac device, you don’t have to concentrate on these partition sizes. If you want to install the WD external hard drive for Mac, consider the steps below.