First, be sure to install Play Framework. I'm using version 2.3.6.
Then, rename conf/application.conf.dist to conf/application.conf and change the dropbox.app values.
dropbox.app.key = "YOUR_APP_KEY"
dropbox.app.secret = "YOUR_APP_SECRET";
dropbox.app.name = "DropboxPlayExample"
dropbox.app.version = "0.0.1"
You shouldn't modify the redirectUri param. The key and the secret values can be retrieved on the dropbox website. name and version can be changed to whatever you like. It will be sent as an header to the Dropbox API.
Launch the Play application and then go to this url http://localhost:9000/dropbox to link your dropbox account. Once you're redirected to the "Auth finished" page, you can display the content of your / directory by going to http://localhost:9000/dropbox/list.
This code is provided as a basic example to get you started with Dropbox and Play, it's not intended to be used in production as it is.