Fuzzball is a Node library. It can only run inside of Node, which is its own platform and not part of the core JavaScript language. Node adds a lot of API and supporting frameworks that are not part of core JavaScript language (like DOM processing).
Drafts’ native JavaScript environment is based on JavaScriptCore and is not appropriate for execution of Node libraries.
In some cases Node libraries provide versions of their library that can run outside of Node, but I don’t see that noted as an option in a quick review of Fuzzball’s read me.