As far as I know, the NTFS file system is treated as “read only” by the MacOS.
If you’re not worried about losing the data on the drive, you can format it to HFS+, but then you’ll have the problem that Windows can’t natively access the drive.
So, you can either download Mac utilities/drivers which will allow you full NTFS access, or you can download Windows drivers which will allow you HFS+ access.
I’ve never used any, so I wouldn’t know which drivers to suggest. Perhaps Google can help.
Sorry… my brain just turned on. I just remembered that if you format the drive to FAT32, then both MacOS and Windows can have full access.