To get your images imported into your store and attached to the correct products your images will need to be named correctly and exist under a single folder available from a public accessible link.
You can use just about any public accessible web location however we recommend the following public hosting solutions for storing your images for import.
Uploading images to S3 is out of the scope for this article, please see How Do I Upload Files and Folders to an S3 Bucket?
Your images will need to have public access enabled - How Do I Edit Public Access Settings for S3 Buckets?
Your images will be available from https://<bucket-name>.s3-<aws-region>.amazonaws.com/<folder>
We recommend using a File Manager plugin to upload files into the wp-content/uploads/<folder> folder on your WordPress site.
Your images will be available from http://<your-wordpress-url>/wp-content/uploads/<folder>/
You can import the image stored on the product in Retail Express into Shopify. To see how to upload a photo to the product in Retail Express refer to this article
The Retail Express product id will need to exist on the product on either the sku or barcode field. We do not support multiple image import due to Retail Express single image limitation.
Your images will be available from https://<your-retail-express-url>/Content/ProductImages/