Clover boots, but not the El Capitan Installer

I'm trying to install El Capitan on a HDD with this setup :
ASUS H170 Pro Gaming LGA1151 Motherboard
Intel i7 6700K CPU clocked at 4 GHz
ASUS ROG Strix GeForce GTX 1060 DirectCU III 6 GB

I did the USB drive with the latest version of El Capitan (fresh download from yesterday) and the latest version of UniBeast by choosing Legacy Mode since Windows 10 is already installed in Legacy Mode on a separated SSD (that I have disconnected temporarily in order to do the El Capitan installation)....

Clover boots, but not the El Capitan Installer