The attachment field type will allow you to attach multiple files directly to your records, including mp3s, PDFs, photos, and word documents. The attachment field looks like this in the expanded record view:

Tapping the camera icon will enable you to take a picture with your phone camera and directly attach it to your record.

Tapping the painting icon will enable you to attach a photo from your phone's files.

Tapping the ellipsis icon will enable you to upload files from a variety of other sources, including from a web search or from your Dropbox or Google Drive account.

The cell will show thumbnail previews of the files you've attached, which you can tap to open in an expanded preview or download directly to your phone.

From the bottom of the expanded preview, you can tap the download icon on the left to bring up a variety of sharing and downloading options, or you can tap the trashcan icon on the right to delete the attachment.