generally speaking, drives running OSX or used exclusively with the apple ecosystem are formatted with HFS+ file system which is incompatible with Windows systems. Windows uses NTFS (newer) or FAT32 (older) file systems. there are utilities that you can use to allow Windows to at least read HFS+ (so you can retrieve the data) and some can read/write, so you can use the drive as an external on either platform. here's a write up on such utilities
if the computer were operable you could log in over the network and have read/write access, as that process somehow handles the file system conversion behind the scenes, but physically mounting a drive on a computer that doesn't understand the file system used is not supported out-the-box on either platform.