Help for integrating the Laravel package
Forum rules: Always add your Laravel, Aimeos and PHP version as well as your environment (Linux/Mac/Win)
Checkout as guest is the default if the user isn't logged in. You can either add a login box to the basket or checkout page template or you can create an intermediate page between basket and checkout where the customer can explicitly decide. In the later case, you need to reconfigure the named route to the checkout in the basket controller.