I believe they come preprogrammed but if not Stmcube programmer and stlink v2 will get you there. There's usually a 3 or 4 pin terminal pad near the stm32 on the board that you can solder in a 3 or 4 pin header to connect the stlink to. Usually labelled VDCG or similar (voltage, data?, clock ...

Hi, I bought the V2 IV board and I have questions:
Is STM32 and AtMega already programmed? (I don t see any installed socket to programm controllers)
And is Atmega programming trough the wifi too?
Thanks