A:Answer I believe most high-capacity Windows-formatted portable hard drives come formatted as NTFS (a common Windows format)
By default, MacOS can read NTFS volumes, not modify or delete files and folders.
You would be able to see the files that the Windows computer created, but not modify them.
So, unless you install a MacOS utility like Tuxera NTFS (very reliable - used it for years), your Mac won't be able to write files to the NTFS volume.
(There are other such utilities, but I can only speak for the Tuxera NTFS, since I bought a license years ago)
If you did install Tuxera NTFS, then on the Mac, the portable drive formatted as NTFS just looks like any volume / drive.
On your Mac, you would be able to read / write / delete files and folders on that portable drive.
You may have to exercise some care, e.g., illegal characters for filenames on Windows, Windows cares more about filename extensions (e.g., Word .doc files. Excel uses .xlxs extensions). In general, MacOS tends to manage things like file extensions for you, but it's something to be aware of.
You can also use a drive partitioning utility to format the drive into two different volumes - one NTFS, and the other MacOS.
This gets into a whole different level of complication - depending on how tech-savvy you are.
Given the cost of drive partitioning utilities, as well as how inexpensive external USB drives are, it might not be worth the effort - you could just buy two drives for example, just formatted differently.
IMO, it's less trouble to get a MacOS utility like Tuxera NTFS, than mess with drive partitioning.
