Digital Module requires its license in addition to the basic oscilloscope license.
Select Digital Module from the modules menu.
You can see a new panel for the digital channels*. In case your oscilloscope has digital inputs you will be able to turn ON/OFF the digital channels and see them on the screen with the analog channels.
* You can see this panel also if the oscilloscope has digital inputs but without the Digital License you cannot access the additional features of this module.
Even if your oscilloscope doesn't have digital inputs, you can convert one of the analog channels to a digital signal with the last control on the panel.
The converted signal will be the Logic Channel 5 (or L5).
Click on the blue channel cursors on the left. On the top on the screen you will see a Settings icon. There you can select the digital channel and apply a protocol decoder.