Hi Bruno,
That is the problem, if you created the USB with Rufus, there are way too many different settings for creating bootable USB's for many situations.
Here are the steps to follow:
Create the USB with the Media Creation Tool
That will always create a UEFI compliant USB
Boot into BIOS, disable that SCM setting permanently and ensure BIOS is in UEFI Mode with Secure Boot (on the Security tab) disabled for the installation
Save those settings and boot from the USB.