I have provided a link to my clients, so they can "Make a Copy" of the board and then edit their copy.
Some don't have the "Make a Copy" button.
I believe your board is set as public, am I right?
A public board can be copied if the user is logged, as you can see on the image the option won't show up if they aren't logged.
If your board isn't public could you open a ticket through the link www.trello.com/contact, please, send their email and the board's link, it'll make the process quicker.