Modules > Amazon > Configure > Marketplace
The Marketplace tab is the tab (or tabs) represented by a flag corresponding to the language used in the marketplace:
For each language configured in Localization > Languages, an additional tab will appear.
You will fill in the Amazon platform and corresponding currency. The currency should match the reality, if it does not exist in your PrestaShop, you need to create it in Localization > Currencies.
API Settings
Fill in the key obtained in Obtaining Amazon keys page.
Then click on “Connectivity Test”:
The message “Connection with Amazon: Ok” must appear if this message does not appear, check your configuration in Information tab.
General Configuration
Default Pricing Rule
Pricing Rule that will apply to all selected categories, if no other pricing rule is found. See the help page on Pricing Rules
Rounding
Rounding Policy to apply, one or two digits, no rounding, or smart rounding, the smart rounding will export intelligible and attractive prices, for example € 15.99 instead of € 15.93
Carrier Mapping
Mapping Example:
Incoming Orders
On the right, the corresponding PrestaShop carrier, ideal to display the correct name on your order page or on the invoice.
Outgoing orders
The field on the left corresponds to the carrier on Amazon, if you do not know what to give, go to Orders > Amazon, list the orders, the fields you will need to map appear in this column: 
On the left, select the carrier in your store that will be used for the order processed. For incompatibility reasons, module carriers are not displayed.
On the right, select the associated Amazon carrier used to notify Amazon.
This list is provided by Amazon and, is fixed.