To get started in terms of what to build, Scrum requires no more than a...

According to the Scrum Guide1, Scrum does not require or provide any specific techniques or methods for product definition. Rather, Scrum provides a framework with roles, rules, and events within which complex products can be developed. To get started in terms of what to build, Scrum requires no more than a Product Owner with enough ideas for a first Sprint, a Development Team to implement those ideas and a Scrum Master to help guide the process.

References: Scrum Guide