i hacve just started with a bluepill verson, 2 nights ago so new to me as well.
firstly i had to get the bits togeather in the arduino ide. there are 2 diiferent versions in the wiki depending which software you have. i had "OnStep 4.x and Later" so i did that.
there are some test files in the files section-https://onstep.groups.io/g/main/files/Utilities%20for%20STM32
i tried to load the blinkey but got an error about the loader not being there.
Please install it or add <STM32CubeProgrammer path>\bin' to your PATH environment:
found a reference to it in the thread firn july " Help with flashing STM32 Blue Pill PCB"
i had to give an email address to get the stmloader from the link but that ran fine.
i could then load the blinky so i knew i had things set. i had to load it then power off change the jumper and i also unpluuged and replugged the usb ( read somwher it helped rest somthing). i also changed the blink patter to check i could edit files .
i then loaded the 64k tester and that worked
loaded 128k tester that worked.
now waiting to get my clockchip connected so i can load and check onstep.
PS , still can't find the bit in groups.io wer i seem to keep changing text size accedently.