Hi criswelld - the voice recording tool is not currently available to ZooBurst users, though you can see how it works by checking out the book above. Audio features will become available when we release the ZooBurst "premium" account at the end of this month. Premium account holders will get unlimited access to the ZooBurst audio recording tool, a searchable sound effects library, and a classroom management feature that lets you create up to 250 student accounts. Student accounts will also have unlimited access to the audio recording tool and sound effects library.
I'm sorry to hear that the book didn't load for you! I just made a change to ZooBurst that should help with loading issues. Could you try it again and let me know if it loads for you? Thanks!