Going forward, you should be able to use the drive and its dual partitions on their respective operating systems. Give your settings a final lookover and click Apply. Then click the second partition, name it Mac and change its format to APFS. Name one partition Windows and change its format to exFAT. For example, you might want more storage for your Mac than you do for your PC. Click the + sign to add a second partition, then drag the lines to adjust the size of each partition. Select the drive from the left sidebar, then click the Partition tab. To do that, connect the empty external HD to your Mac and launch Disk Utility.
You won't be able to write to the Mac side from your Windows computer, and vice versa, but it's a good solution for people who want all the advantages each format has to offer for its respective system.
For example, if you have a 1TB hard drive, 500GB of storage can be used with your Windows computer, and 500 will be dedicated to your Mac computer. This solution is a little different than the previous two because instead of having one hard drive that works with both machines, you're splitting your HD into two sections, each dedicated to a different OS. Option 3: Create two partitions on your hard drive to use with each OS, separately. You aren't stuck with your drive formatted for one platform forever.
