Level 88
The package you describe is not really suited for Laravel. You can use it, but you need to write a lot yourself.
However, this package is a good implementation for that: https://github.com/srmklive/laravel-paypal
I'm also a big fan of Mollie. They offer more than just PayPal and have a very good documentation: https://packalyst.com/packages/package/mollie/laravel-mollie