How can I increase the upload capability to the form to upload mp3 files?

Please check these guides: 

1) https://www.jotform.com/help/29-Upload-Field-Allowed-File-Types 

2) https://www.jotform.com/help/33-Changing-the-Upload-Size-Limit 

If you need anything else please open a new thread, we will be glad to assist you.