Since version 2.3, MP3 Audio Player Pro support Advanced Custom Fields (ACF).
To use ACF fields in the player, you must embed the player through a shortcode.
[sonaar_audioplayer albums="666" feed="acf_audiolink" feed_title="acf_audiotitle" feed_img="acf_image" artwork="acf_artwork" sticky_player="true" show_playlist="true"]
The shortcode attributes that support ACF are:
feed shall return your audio file URL
feed_title shall return your track title
feed_img shall return your track image URL (optional)
artwork shall return your playlist artwork URL (optional)
It's very important that your ACF field names BEGIN with acf_ (eg: acf_audiolink)