Setting up Docker 17.03 CE on Ubuntu 16.04

I’m trying to set up ShinyProxy on an Ubuntu VBox machine. Ubuntu is 16.04. Following everything goes fine, up to but not including the step where I try and change the port (Docker startup section) with the line

ExecStart=/usr/bin/docker daemon -H fd:// -D -H tcp://

results in a message

-bash: /usr/bin/daemon: no such file or directory

Tried to replace the ‘/usr/bin/docker daemon’ with a suitable call to dockerd (as ‘docker daemon’ seems to be deprecated between the time of writing the page i was following and Docker 17.X), but couldn’t find out what the correct options are. Anyone had the same problem, and found a solution?