By default, only FBM orders flow through to Shopify. To also bring FBA orders into the app and forward them to Shopify, turn on the two FBA sync toggles. Enable both for the full Amazon → app → Shopify path.
For privacy, Amazon does not share buyer names with sellers on FBA orders, so on Shopify the customer name on a synced FBA order is set to "Customer / Customer" by default. You can customise this default name to anything that fits your workflow (e.g., your store name or "Amazon Buyer").
The customer-name override applies to FBA orders only. FBM orders continue to receive the actual buyer name from Amazon.