How to connect CSL Pedals to PC directly via USB?

The CSL Pedals, without any addons, do not feature an USB port and cannot be connected directly to the PC. 

Please check the product description on the website (compatibility section):
"The CSL Pedals package does not come with a USB connector and must be connected directly to a compatible Fanatec Wheel Base. To operate as a standalone input device, use the ClubSport USB Adapter (available separately) or the CSL Pedals Load Cell Kit (sold separately). The Load Cell Kit adds a USB connector."

Therefore, you need the CSL Pedals Load Cell Kit or the ClubSport USB adapter to make the CSL Pedals compatible as a PC standalone device, connected by USB.