You can create orders off of Etsy and email a link directly to them so that they can access and edit the file.
To create an order off of Etsy, open up View Orders and select Create New Order (top RH side of the popup window). Enter the customer email, check the Send Email box, then add the item/items and save.
An email will be sent immediately to the customer with a link for them to access and personalize the item. You will see the newly created order listed under View Orders, along with your other orders.
Identify orders that have been created off of Etsy by the order ID, which will have a CJ in front of the order number (found under View Orders).