Arduino for STM32

I'm looking for help, because I can not flash the FYSETC S6 V2.1, when trying to do so I get the error mesage.

Technically very limited with Arduino, SMT32cubeprogrammer and FYSETC . My project is a OnStep telescope mount modification to remove DC motors for stepper motors. but need to flash board so I can table test the kit before installation.
For this project I have followed the OnStep instrucctions "For the STM32F446 FYSETC S6:" in https://onstep.groups.io/g/main/wiki/3915

If any recomendation or help is given I will appreciate to consider my limitations so I can follow the instructions/recomendations.

All comments and help will be very well appreciated.
Miguel.

It seems you didn't properly in bootloader mode.
You have to do this as stated in the wiki:

For the S6 v2 there is a three position pin header. jumper the LEFT (3.3V pin) to the center (BOOT0) to have it enter DFU mode then power on or reset. Once done flashing remove the jumper for RUN mode.