The Raspberry Pi comes with USB HID ports … Restart emulationstation from within the ES interface or restart the retropie from the terminal with sudo reboot. On first boot you will be prompted to configure a controller in EmulationStation.
Just as the Raspberry Pi the ControlBlock provides a USB connector for the power supply. Nintendo Switch Pro Controller Native, USB Works via Bluetooth.
In other cases, you may just have an old controller that needs a little help. … ), the box next to it should change from “OFF” to “ON“.