In the beginning set up choosing type of files in the plugin media settings that users can upload. Also set a max size of file:
Then open the Form settings and add a custom field with form element “File upload”:
As sample I chose ‘rh_file_uploaded’ meta key.
To show audio player for MP3 files you need make next: insert the shortcode below into Theme options -> Ads options -> Before content area or After post area:
[audio mp3="[wpsm_custom_meta field='rh_file_uploaded']"][/audio]
Replace ‘rh_file_uploaded’ meta key with yours and you will see such media player in the bottom of the page: