well, you see that bz2-folder inside that freak_fortress_2.zip ?
You need upload inside that folder, all content in your dropbox tf folder
...Public/tf/materials
...Public/tf/models
...Public/tf/sound
You need keep those all folder paths right.
Maybe easier to use now that dropbox program and syncronize it. If you did install it on your computer ?
And rest of folders and files from zip goes to inside your server tf.
Or that newest plugin. Add it in ...tf/addons/sourcemod/plugins.