By now, Dropbox has no support for KDE's file manager Dolphin, as it offers support only for Gnome's Nautilus. But fear not, as there are solutions for this problem. First, you should follow the instructions from the Dropbox official website. Those instructions state that you should download the dropbox application using the following command (for 64bit):
cd ~ && wget -O - "https://www.dropbox.com/download?plat=lnx.x86_64" | tar xzf -
After the download finishes, you should run the daemon with the command:
At this point, Dropbox started, but it is running as long as the above script is running too. Thus, in order to have Dropbox automatically starting with the system, you will have to add a symbolic link to the KDE's autostart scripts using the following command:
ln -s ~/.dropbox-dist/dropboxd ~/.config/autostart-scripts/
Now, an ls -l command in the /.config/autostart-scripts/ directory should show your newly added script for Dropbox:
alexandru@debian:~/.config/autostart-scripts$ ls -l total 0 lrwxrwxrwx 1 alexandru alexandru 38 Sep 30 00:08 dropboxd -> ~/.dropbox-dist/dropboxd
Now, after restart, Dropbox should run right away.