But which one do you use in Cubase? I assume the Scarlett.
Please have a look at this overwhelming graphic.
It depicts that Cubase uses an audio system that is independent of Windows’ system (where OBS exists).
Generally you need to be able to get the signal that Cubase outputs to the interface on the ASIO side back to the input of the audio interface, preferrably to the Windows side. This is indicated by the “loopback” line.
Your Scarlett does not have a software loopback function but Focusrite recommends to connect the SPDIF out with the SPDIF in by means of a coaxial cable.
There are other software solutions to achieve a loopback. One is called ASIO Linkpro, but it might be complicated to setup. Another is called Voicemeter Banana. Yet another solution is a plugin called ReaStream (from Cockos). This plugin uses a software network connection rather than an audio device to let you “stream” the signal from Cubase to the Windows Audio System.
If you are looking how to setup Cubase when using anything but ReaStream, check this out:
For setting up Cubase with ReaStream look here: