How to setup files upload

Open your ChronoForms7 form "Settings" 

Make sure the "Upload Files" behavior is enabled.

Go to the form "Pages" area *Select Fields

Drag a File field to the "Views" area

Open the file field settings and open the "Advanced Settings" section

Select "Accepted Extensions & Size"

In the "File upload extensions", write the extensions you want the file field to accept, then enter the maximum file size to allow.