Key ID and secret not showing on configuration page

Hello,

Thank you for this module. I am unable to get it to work. When I go to
admin/commerce/config/payment-gateways/add

I don't see any input fields for KeyID and Secret. There is no change at all and the previous selected PG configuration shows.

Maybe I am missing a step.

Steps to reproduce

Install fresh drupal 8 through composer
Install commerce core and cart etc.
added /modules/custom/*/composer.json in merge section of composer.json in drupal docroot as per readme file.
run composer update
install commerce razorpay module through composer
navigate to admin/commerce/config/payment-gateways/add

further, if you click on save after selecting razorpay, the server throws a 500 error
[proxy_fcgi:error] [pid 23838:tid 140514561033984] [client 103.214.61.58:57162] AH01071: Got error 'PHP message: PHP Fatal error: Declaration of Drupal\\commerce_razorpay\\Plugin\\Commerce\\PaymentGateway\\RazorpayRedirect::create(Symfony\\Component\\DependencyInjection\\ContainerInterface $container) must be compatible with Drupal\\commerce_payment\\Plugin\\Commerce\\PaymentGateway\\PaymentGatewayBase::create(Symfony\\Component\\DependencyInjection\\ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) in /home/demo/public_html/com8/web/modules/contrib/commerce_razorpay/src/Plugin/Commerce/PaymentGateway/RazorpayRedirect.php on line 33'