Create a websites
user.
sudo adduser --disabled-password --home /src/websites websites
Login and install dropbox.
sudo -s su - websites
cd ~ && wget -O - "https://www.dropbox.com/download?plat=lnx.x86_64" | tar xzf -
Logged as the websites
user, install the dropbox cli tool
mkdir bin
cd bin
wget https://www.dropbox.com/download?dl=packages/dropbox.py
chmod +x dropbox.py