First, you need to have a working elixir environment:
https://elixir-lang.org/install.html
mix deps.get
mix compile
mix run --no-halt
Create an application on https://scalingo.com, then:
git remote add scalingo git@scalingo.com:<name_of_your_app>.git
git push scalingo master
And that's it!
The application is running at this url: https://sample-elixir-plug.scalingo.io/
https://elixir-lang.org https://github.com/elixir-plug/plug