ESP32 Saola 1M PINS

Hello,   I am really new to the word of MCU and how to work on them. I am working on a project for my thesis and I have decided to use the ESP32 S2 Saola  board with the ADS1294 sensor to produce an ECG. My sensor takes analog inputs and through an internal delta sigma ADC I get a digital output. In order to connect my sensor to the Saola board I should use the 33-34-35-36 pins? Does this pins(33 to 36) represent the SPI interface? And what exactly is the use of the 46 pin ? Thanks in advance for your time! Orestis V.