A:Answer Transferring is simple, e.g., I using File Explorer. Keep in mind, if you have an old machine with only 2.0 USB ports, moving a ton of files will be slow, but not too bad.
Not too sure why your Seagate doesn't work, perhaps it needs to be reformatted to NTFS, if so you'll need to offload your files ahead of time as reformatting will delete everything.