The functionality of "File Upload" in the app is for uploading files from the Update Client Details Form to the specific Salesforce record. 

A user may also want to upload files in the record for further use, so this feature will help the user to fulfill that purpose. 

The user can upload a file up to the size of 10 MB and remove them as well before submitting the form.

This setting can be enabled from the about page configuration settings.