Hi Dewi_GZ,
Thank you for reaching out to us about the Microsoft Merchant Center feature! I'm here to help!
Currently, the Microsoft Merchant Center and Shopping Campaigns are available in the following countries/markets: the United States on PCs, tablets, and smartphones, and in the United Kingdom, Australia, France, Germany, India, and Canada (English only and excluding Quebec) on PCs and tablets.
However, if your customer is planning on advertising to the U.S. market, we can get this feature enabled for you. Please respond to my private message to move forward.
Sincerely,