Hello Fran_briz
Just have a look here
The PCM5102A works in stereo with pin as follow
PI0 → I2S SCK–>pin29
PI1 → I2S BCK–>pin12
PI2 → I2S LCK–>pin35
PI3 → I2S DATA–>pin40
5V → to VIN power of DAC board–>pin2
GND → to GND power of DAC board-->pin6