Contact form 7 field repeater plugin allows creating one or more fields dynamically.
It is easy to use and lightweight plugin.
Demo: Cf7 Repeater

How to use contact form 7 field repeater?

Upload the zip file to your WordPress website and activate it.
Add the shortcode in contact form 7 tags as follows.
Example : [repeat demo1 demo2 ]
*Note: Here demo1 and demo2 are adjacent field names.
We must add field names to the email message body and attach a field names to file attachments.
We can adjust the position of buttons or fields by style.css of your theme file.  Add label tag as in the picture.

Demo : Cf7 Repeater

Only $19 for the unlimited installation license.