Hello, glad to help you. Firstly, you need to know the NTFS drive format only has full read-and-write support on Windows. And if you want to use the drive for both Mac and PC, you can consider these fixes below:
(1)Use NTFS driver for Mac like iBoysoft NTFS for Mac. Using this tool you needn't format the drive, which will lose all your data. You can easily use your external drive on Mac with iBoysoft NTFS for Mac and use it normally on Windows as before.
(2)Format your drive on Mac with Terminal or Disk Utility. And you are suggested to format it to exFAT or FAT32. But you must back up all data before this step.
(3)Format your drive on your Windows PC. The tool Disk Management can help you.
Also read: What's the Best Format for Both Mac and PC?
