To enable online payments in your Wix store and start selling, you need a premium subscription. You can choose from the Business VIP, Business Unlimited or Business Basic plans from the Wix Business & eCommerce plans. All these plans allow you to connect with Gelato and add products to your store. For more information, please visit Wix Help Center:
In general, to upgrade your existing Wix site with a store, you'll need to:
Add the Wix Stores app
Select a business premium plan