1 TB Nas Trouble With Read Write

I am having some trouble with a NAS i have. After a few days I figured out the best way to connect to it FTP. I have set up a FTP username and password and have given it Read Write privileges yet when I try to take i file from my MacBook to the drive it says " 'Public' (folder name) can not be modified". Any one offer any suggestions? Is the router blocking the read write privileges?

I should note from my windows machine i can write to the drive (transfer a file). Is the MacBook blocking anything?