Log in to your Amazon shopping account, then click on the menu dropdown (indicated below);
In the left hand menu column, scroll down to the section "Help & Settings", then click on the option "Your Account";
The web page will now be headed "Your Account" and will present account based setting options.
Select the option "Login & Security";
Scroll down to the setting "Passkey", then click on the "Set up" button (indicated below);
Your Fido2 key will be using the Passkey authentication method so we now need to click on 
You will now be asked to confirm that you wish to create a passkey, and by default the password manager would be used, but we want to use our Fido2 key, so click 
;
Expand the option "Windows Hello or external security key" (indicated below);
We will be storing the encryption keys locally on our Fido2 key, so click on "Security key", then click 
;
You are now notified that access to Amazon will be prepared with your Fido2 security key - click 
to proceed to the next step;
You will now be asked to give permission for your Fido2 key to be examined, insert the key into a USB port then click ;
At this point you will be asked to provide the PIN code that protects your Fido2 key;
Enter the PIN code for your key then click 
, and you will be asked to touch the button on your key (if your model has a fingerprint reader you may be asked to provide a finger swipe instead);
Provided you press the button on the Fido2 key in the allowed time, the passkey details will be stored on your Fido2 key, and you will be presented with the following confirmation;
Click "OK", and you will be shown the final confirmation that the Fido2 key is now able to be used as an authentication method.
