To limit the attachment upload to a specific file format, go to:
Click an attachment field.
Upload settings section.
Set Restrict Attachment Types To
This option is used to restrict the type of files allowed to be uploaded in an attachment field (e.g. limit it to images, videos, audio, documents).
💡Note for Audio file
MIME types are used to determine if the file uploaded to the attachment field is audio. Here are the file extensions acknowledge as audio: au, snd, Linear PCM, mid, rmi, mp3, mp4 audio, aif, aifc, aiff, m3u, ra, ram, Ogg Vorbis, Vorbis, and wav.
💡Note for Compressed file
As of the moment, the only supported file extension is zip.