Securesocial and playframework - how do i install?

Question

This is silly - how do i install secruesocial for playframework 2.5?

This page - https://playframework.com/modules/securesocial-0.2.4/home - is entirely unhelpful.

I don't know what "play deps" means, where to run it from, or where the play.exe file even is. I'm using "activator start" to start my play server... is play deps something else?

I also don't know what/where the dependencies.yml file is, or how i'm meant to add an entry to it!