Arduino for STM32

Thanks a lot for the fast answer. Looks like I made a mess with the cores.

Hello everybody.
Sorry if this has been answered before and I have not found it. Furthermore, I'm pretty new to Arduino, so maybe the question is trivial.

I am using the Arduino IDE on a Mac to program an STM32F103C8 Black Pill. I installed the standard STM32 Cores from STMicroelectronics version ...