You will need to use product slug or ID to import reviews for your WooCommerce products
1. Get WooCommerce product's slug
Login to your WordPress admin > Products > All products
2. Hover on a product that you want to get slug, click on "Quick edit" then you can see Slug of product
2. Get WooCommerce product's ID
Login to your WordPress admin > Products > All products
2. Hover on a product that you want to get the product's ID then you can see the ID of the product
All the best,
Ryviu team.