I am sorry this is so much work. It used to be quite straightforward...
Have you made sure you downloaded the Play tgz version and are have that set up as your default Play ?
The library I am using should just work with that, and I am surprised that all the dependencies are not in there already.
What we have written is a play app, that turns it into an LDP server. IT's really a bit heavy handed, as play is already a web server in a way, but it was interesting at the time for people who may have wanted to use play to run normal apps.
NP. It's more due to my lack of understanding of Play and the way SBT handles dependencies. I asked some questions in the Play gitter channel but did not receive an answer. I'll next try in the Scala channel.