Problem Installing Amazon Pay Module Using Composer for Magento 2

I am trying to install a website from server to localhost. When I run the command composer update in git-bash then I get the following error.

=> Screenshot :

All the other modules got installed properly but amazon-pay-sdk-php is causing issue.
I have checked several threads similar to this issue, found many answers but none worked in my case.

=> composer.json file :

{
"name": "magento/project-community-edition",
"description": "eCommerce Platform for Growth (Community Edition)",
"type": "project",
"version": "2.1.11",
"license": [
    "OSL-3.0",
    "AFL-3.0"
],
"require": {
    "magento/product-community-edition": "2.1.12",
    "composer/composer": "@alpha",
    "magepal/magento2-customshippingrate": "^1.3",
    "mestrona/magento-module-categoryredirect": "^2.1",
    "amzn/amazon-pay-and-login-with-amazon-core-module": "1.2.5",
    "amzn/login-with-amazon-module": "1.2.5",
    "amzn/amazon-pay-module": "1.2.5"
},
"require-dev": {
    "phpunit/phpunit": "4.1.0",
    "squizlabs/php_codesniffer": "1.5.3",
    "phpmd/phpmd": "@stable",
    "pdepend/pdepend": "2.4.0",
    "fabpot/php-cs-fixer": "~1.2",
    "lusitanian/oauth": "~0.3 <=0.7.0",
    "sebastian/phpcpd": "2.0.0"
},
"config": {
    "use-include-path": true
},
"autoload": {
    "psr-4": {
        "Magento\\Framework\\": "lib/internal/Magento/Framework/",
        "Magento\\Setup\\": "setup/src/Magento/Setup/",
        "Magento\\": "app/code/Magento/"
    },
    "psr-0": {
        "": "app/code/"
    },
    "files": [
        "app/etc/NonComposerComponentRegistration.php"
    ]
},
"autoload-dev": {
    "psr-4": {
        "Magento\\Sniffs\\": "dev/tests/static/framework/Magento/Sniffs/",
        "Magento\\Tools\\": "dev/tools/Magento/Tools/",
        "Magento\\Tools\\Sanity\\": "dev/build/publication/sanity/Magento/Tools/Sanity/",
        "Magento\\TestFramework\\Inspection\\": "dev/tests/static/framework/Magento/TestFramework/Inspection/",
        "Magento\\TestFramework\\Utility\\": "dev/tests/static/framework/Magento/TestFramework/Utility/"
    }
},
"minimum-stability": "alpha",
"prefer-stable": true,
"repositories": [
    {
        "type": "composer",
        "url": "https://repo.magento.com/"
    }
],
"extra": {
    "magento-force": "override"
}

}

I understand the error message that composer is looking for "amzn/amazon-pay-and-login-with-amazon-core-module" and it could not find it but then what should I use in place of the above module name.

So basically my question is how I can install amazon pay and login module on localhost. Should I change "amzn/amazon-pay-and-login-with-amazon-core-module" to different module name as composer could not find any module with above name, or if there is any other method.

If anyone have any idea then please guide me in the right direction. I am really stuck into it.