In order to have Integration Manager sync inventory between your WMS and your Wix cart, you must enable the option to manage variants and track inventory in your Wix Store.
Wix Store gives you the option to manage variants only if our product has variants; otherwise it will give you the option to track inventory.
Failing to enable "manage variants" will prevent us from seeing all the variant SKUs your products have, and thus we won't be able to properly perform inventory updates for them.
Wix allows for multiple "Variants" on a single product. These should be used for things like different sizes or colors of a product.
Each Variant should have a unique SKU or inventory may not be tracked properly.
By default Integration Manager picks up open "Paid" orders. If you won't be charging customer's credit cards until after the order is shipped, change the "Financial Status" field in Integration Manager to "Pending" or "Not Paid".