Creating a memstick of Pfsense, create only two files

I want to install the Pfsense OS on a server but when I try creating a bootable USB, I have only two files :

EFISYS (F:) │ └───efi     |        └───boot         |   BOOTx64.efi         |   startup.nsh 

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I’m using this image pfSense-CE-memstick-2.4.4-RELEASE-p1-amd64.img (748 Mo) and I use Rufus for creating bootable memstick. The memstick is 32 Go. I don’t know if it’s normal.