If you are subscribed to a collection, visiting that collections page will show that you are subscribed, and take you to subscription management.
http://localhost:8080/dspace-freemarkerui-webapp-1.7.0-SNAPSHOT/subscribe
However you can't subscribe to any new collections. Which is counter to the advice given: "To subscribe to a collection, visit the collection's home page, and click on the "Subscribe" button."
Also you can unsubscribe from an individual collection, but clicking Remove All Subscriptions resulted in an error.