Besides the Attachments object, the Files object can receive data sent through the form as well. To set it up, just follow the steps below:
1. In the Object Mapping section, add the Content Version object.
2. Associate the Salesforce fields with the fields indicated in this image:
The Path on client field can be mapped to any input field, the Content Origin and Content Location fields will be associated exactly like in the example above. Version Data has to be always mapped to an upload field.