Email them and tell them you want to promote some of their products (stores) but need to have the specifics before you can build the website.
That's what I did awhile back. All I had was Internet marketing sites and wanted to do something different so I emailed them and told them I wanted to build a site for it but I needed the products info to build it.
The old ... Which came first? ... The Chicken OR the Egg?
Good Luck!