Older versions of Cubase (pre-12) used a physical USB dongle. Cubase 11 straddles the line. Many boxed versions require the (blue dongle). You plug the dongle in, run the eLicenser Control Center, and deposit the license onto the physical stick. Without that stick, the software won't open.

Activating Cubase 11 involves a specific, often misunderstood process using the eLicenser Control Center (eLCC)

You don't type the code into Cubase itself. You type it into the (a separate application). If you haven't installed that, Cubase will never see your code.