You have the firmware in raw binary format file. You need to load it on flash at address that different from base address for Stm32 flash memory 0x08000000.
When you open the file select dialog and select file in raw binary format then the application set load address automatically. If the firmware is selected first time then the application set load address equal to base address of flash memory for Stm32 CPU 0x08000000.
You can see load address in the special area on right side of screen.
If you need change the load address just tap on this area. The dialog for setting load address wil be shown.
Input correct load address and press button "OK". New address will be set. You be able see that in the special area.
Now when you press button "Load file to flash" then firmware will be loaded at this new address.