You need to have confluence linked to other applications. To do this, you'll have to navigate to t he administration console. Go to edit -> administration -> site administration. Log in with administrator credentials, and then scroll all the way down to the bottom of the left-hand menu. There should be a link, under the Administration heading, which says "Application Links." If you click that you can then add application links.
The hamburger button won't display until you have at least one application linked to confluence.