Sign in to the your Login.Gov account, then in the "Your Account" column, select the option "Add security key" (if your account has only just been created, then you will be presented with a list of options, select the option "Security key");
Provide a suitable name for your Fido key;

You will then be asked to select where to save the passkey, select "Security key";

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;
