Add new Gateway

I’m trying to add a new gateway via plugin.

I created the plugin with the following code:

https://pastebin.com/zbjHqHKy

And in the file class-rcp-payment-gateway-paypal-brl.php

I put the class:

https://pastebin.com/afuBEZCp

The problem is that I get the following error:

Fatal error: Class ‘RCP_Payment_Gateway’ not found in … wp-content / plugins / zrcp-paypal-brl_d2 / class-rcp-payment-gateway-paypal-brl.php on line 12

That is, how do I get the RCP_Payment_Gateway class and extend it in my plugin?

If I do an include or something like that it will give error later because it will try to make the include again in the original RCP plugin.