Yours Board's FPGA Doesn't have any circuit to play music so it uses an Audio codec to do this job. It must be noted that the board contain Audio CODEC "Realtek ALC272VA3-GR" therefore its gives sound so i think you first see the connection of this IC(Audio codec) to your FPGA,then give input to those pin which connect to this Codec IC.
The link to your Audio Codec Datasheet is here