Actually, you are not allowed to copy files from Mac to an NTFS formatted drive. Mac only supports you to read an NTFS drive but write on it. You need to use an NTFS reader for help.
iBoysoft NTFS for Mac allows you to view and copy files from an NTFS-formatted external drive on Mac. It is also an NTFS writer that enables NTFS to write support on Mac. With it, you will have full read and write control over the Windows NTFS file system in a macOS environment without formatting it with a Mac-compatible file system.
Following the below steps to mount your NTFS drive in read-write mode on your Mac.
Step 1: Free download, install, and launch iBoysoft NTFS for Mac.
Step 2: Connect your external hard drive to your Mac.
Step 3: Wait for it to mount successfully.
After that, you can copy files from your Mac to an NTFS-formatted drive.
Instead of that, you can also format your external hard drive with a Mac-compatible file system so that you can access the NTFS drive and copy files to it.