CAN'T figure out how to drag a folder and DROP it into the drive

I got this WD passport ultra external harddrive to back up some of my files.
I can’t for the life of me figure out how to use this.
I drag my folder from anywhere else and try to drop it in and I get the circle with line going slanted - rejecting my folders.
I downloaded the WD security and Drive utilites.
I don’t know what to do!!! HELP!

You got a WD Passport Ultra for MAC?

If I recall correctly, that drive is formatted with NTFS. If you didn’t install NTFS drivers, you won’t be able to write to it.

The other option is to reformat it to be Mac compatible.