bundle exec rake error

I am trying to setup harry's referral system http://ift.tt/1pwW30B on aws server. While setting up database using postgresql and after submitting command bundle exec rake db:create, it gives me following error:

 fe_sendauth: no password supplied

/home/ubuntu/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5.2/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in initialize' /home/ubuntu/.rvm/gems/ruby-2.3.0/gems/activerecord- /home/ubuntu/.rvm/gems/ruby-2.3.0/bin/rake:23:inload' /home/ubuntu/.rvm/gems/ruby-2.3.0/bin/rake:23:in <main>' /home/ubuntu/.rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:ineval' /home/ubuntu/.rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `' Couldn't create database for {"adapter"=>"postgresql", "database"=>"prelaunchr_test", "host"=>"localhost"}