There's no firmware update for the SU-9:
View attachment 219503
There
is a USB driver to unlock the native ASIO interface and stuff, but that's not something you "upload to the USB connected SU-9". It's something you install on your PC.
Please make sure you've downloaded the "SMSLUSBAudioDriver.zip" file.
Extract it using 7zip or similar, then right-click the "XMOS_USBAudio_v5.40.0_2022-06-15_setup.exe" file-> "run as Administrator".