I don't have Cubase loaded on this computer, so going by memory...
Devices> Device Setup...> VST Audio System > Select your interface's ASIO driver.
then
Devices> VST Connections> Add the Input channels of your interface. For the Scarlett Studiom, it's probably one or two channels. Do the same for the Output.
Create a track and select the appropriate channel. and Mono or Stereo. Tip: Mics are mono.