Enable client to download completed form?

Is this possible that after a client has completed a multipage form they can download the summary?

Yes, you can create an autoresponder notification: https://www.jotform.com/help/26-Creating-a-Form-Autoresponder, where you can attach the PDF submission file: 

(Second option from advanced settings)

Open a new thread if you need anything else, we will be glad to assist you.