Create ftp user on symbolic link folder in Ubuntu

You cannot create or give ftp access to a folder that is a symbolic link. The solution is to use the mount command with the bind:

create the folder in the destination path first

sudu mkdir /destination/path/folder_name
enter system password

give access to the folder:
sudo chmod -R 777  /destination/path/folder_name

Then, mount folder to the destination path

sudo mount --bind /path/to/original/folder  /destination/path/folder_name