Time tracking is, rather unhelpfully, not added as standard in Kanban Projects, which is not ideal when it comes to measuring velocity.
Here's how to get it...
Go to your project and select "Project Settings" from the sidebar. Then, click your way to your screen and configure it (e.g. (from Sidebar in Project Settings) Screens -> [pencil icon next to the screen scheme] -> click on desired screen -> Select "Time Tracking" )