As mentioned before, the Kepler - Attachment fields | simple & multiple custom field can be configured to store multiple files.
Step 1: Click on Attach files Icon 
and select files.
Step 2: Choose one, or multiple files from the opening window or, drag and drop your Files.
Step 3: At this step, you can:
1. Delete files from the custom field.
2. Preview images or download other file types
3- Empty File Warning that alerts users when attempting to attach empty files to an issue, the attachment process is not blocked so users can proceed as needed.
Screenshot below shows empty files "Exemple.txt" and "E.txt" . Empty means the size is 0 KB.
Step 4: The Attach File Manager controls automatically the attachments according to the administrator's configuration, and displays error messages in case of files that do not correspond to the field configuration.
Case 1: Files extensions are different from the configuration.
Case 2: The sum of all sizes is greater than the defined one
