Here is a quick overview of how to upload or sync products from WooCommerce and Shopify to Google Merchant Center and auto update periodically.
But before you start setting up your store with Google merchant center – you must have installed product merchant JSON-LD or product schema on your store on all product pages. Also there should not be any syntax error.
So.. it is better to run the schema test with Google schema testing tool before you start setting up your store with Google merchant center for free.