To get your Shopify products appear on our app, your Shopify products must be published, must have an "active" status with quantity/stock of at least "1" or more in your inventory. We're unable to import zero quantity listings. You can also follow this link below on how to manage inventory or assign value in your quantity from your Shopify.
https://help.shopify.com/en/manual/products/inventory/managing-inventory-quantities/bulk-editing-inventory
Please check out this video.
Screenshot Guide: