In order to transfer audio data in real time (i.e., record AUDIO TRACKS) you will need a separate audio interface. It does not allow you to route audio from the synthesizer into the computer. This means when you reopen the Project you can have the Editor's total recall feature restore all the settings to your synthesizer just as they were when you completed work. The advantage in addition to all the signal routing and processing functions is that you do not have to bother save a separate file for your synthesizer, because when you save your Cubase Project it will automatically save all the settings for your S90 XS/S70 XS and keep them bundled together in the Cubase Project (.CPR) file. Or, as is outlined in this article, Cubase can encompass the Editor as a VSTi – which runs inside the DAW's environment. It can be run as a standalone application. (The Editor can be used with or without Cubase).

This will facilitate MIDI recording and use of the Editor VST. This guide will take you through setting up your computer for MIDI communication with the S90 XS/S70 XS. USB-MIDI QUICK SETUP GUIDE - Cubase AI and Editor VST

How to install yamaha usb midi driver