OSX does not support writing to NTFS, it will read it however. You will have to format it as FAT32.
That also means that you can't use files over 4GB without them being split to under 4GB.
There were a few programs you could install to allow OSX to read/write NTFS but some of those were a bit sketchy, at least in my experience. Drives becoming unmounted when trying to read/write to them, odd things like that. They may have gotten better but I have been out of the Apple world for a while.