HFSExplorer unfortunately requires you install Java to use it, but it’s the only free option here.
If you only have Windows systems available, you can use HFSExplorer to copy files from the drive onto your Windows system drive or another drive. If you have a Mac lying around, you can plug the drive into a Mac and back up the files. Instead, we’ll just be wiping the drive and starting over from scratch.
This process won’t actually convert the file system. First, back up the data on the Mac-formatted drive if you have anything important on it.