Preliminary Remarks
Amazon Pay separates sandbox and production view in the so-called Integration Central. The drop-down menu in the header can be used to switch between the sandbox view and the production view.
Accordingly, there are also two views in Integration Central, which are also marked with either Sandbox environment or Live environment.

Note: This article describes the linking of the sandbox environment from Amazon Pay with the stage backend from Frisbii Media. The steps shown are identical to the live environment of Amazon Pay and the live backend of Frisbii Media. We recommend testing the implementation on the stage system first before using Amazon Pay as a payment method on Frisbii Media's live system.
API credentials and API key
Use the vertical lines at the top left to expand the menu.
Navigate to Integration Central.

Under Guides, keys and IDs to link your store:
Select Self-developed as Ecommerce provider or integration type using the drop down menu.
Select Recurring/Automatic payments as Payment type.
Under API credentials:
Click on Add Store ID.
Enter all the required data and save.
Return to Integration central.
Copy the Store ID and Merchant ID. Both will be needed later in the Frisbii Media Merchant Backend.

Create API key
Click on Create key. A dialog box opens.
Select Generate API credentials.
Enter a name for API key.
In the Existing API keys area, the Public Key ID created is displayed.

Private key
The private key is automatically downloaded as a file (extension: .pem) when the public key is created.
Check your downloads.
Open the private key file in a text editor software and save it somewhere save.
Note
The private key file cannot be downloaded a second time. If the file is lost, a new key pair must be generated.
Webhook configuration
For Frisbii Media to be able to receive information on failed payments, a webhook URL must be registered in the Amazon account.
Get the webhook URL from the Merchant Backend
You can find the webhook URL in the Frisbii Media Merchant Backend via Settings → Financial → Payment Methods → Amazon Pay in the editing mode.
For stage: https://app.frisbii-media-stage.com/callbacks/v1.0/amazonPay/companyURL
For live: https://app.frisbii-media.com/callbacks/v1.0/amazonPay/companyURL
Store the webhook URL in Amazon Pay Account
Click on the gear symbol.
Click on Integration Settings.
Under Instant Notification Settings, click on Edit.
Enter the webhook URL and save.

Connecting Amazon Pay to Frisbii Media Merchant Backend
The data just created in the Amazon Pay account now need to be linked in the Frisbii Media Merchant Backend.

In the Merchant Backend, open Settings → Financial → Payment Methods → Amazon Pay.
Click on Edit.
Fill in all fields with the relevant data.
Note
The content in the Private Key file must be entered in full - including the lines -----BEGIN PRIVATE KEY---- and ----END PRIVATE KEY----- - in the Private Key field.