Quote Originally Posted by Pavelev View Post
What Firmware should I download and how to install it.

I need step-by-step advice on how to proceed and what to do.
Here is a video on setting up the FYSETC S6: Fysetc F6 - HOW TO INSTALL on a 3DPrinter (Ender3) - YouTube .
I personally would find the absolute latest version of marlin. I think it is up to 2.0.7.2 and configure that and I would also use platformIO to manipulate and flash said marlin. And here is a video on that: https://www.youtube.com/watch?v=W6zYvRgGr3Q&t=