Set up an Online Payment System With a Simple Payment Button

The Simple Payment Button helps you embed a payment system into your site without needing to set up a full store. This allows your customers to submit their payments with the click of a button, and you’ll receive each payment via your PayPal account.

Jason & Company Plan for WordPress 5.0

if you see code in the editor after the update to WordPress 5.0 install Classic Editor plugin 

https://wordpress.org/plugins/classic-editor/

https://www.siteground.com/blog/wordpress-5/