This is almost the same as paypal checkout provided by copilot but tailored to only support one time payments, (only paypal buttons) also it doesn't show the shipping address for those websites who have no shipping process
Any extra info not found in instructions might be found in paypal checkout plugin page

Instructions:
1. Create PayPal developer account
2. Create REST API application (Both live and sandbox)
3. Copy Sandbox Client Id and Live Client Id to the plugin tap (in the -dev when you are developing and in the other ones when you deploy live)
4. For Client Id Headers put the client id that you will use for now (if you're developing mostly you would use your sandbox client id and when you are deploying live mostly you would use your live client id)
5.Draw the element on the payment page and make sure its height is good enough (about 630px)
6. Set the amount + the currency + etc.
7. In the workflow on page load add the action get access token (Use the one in the plugins tap not the one in payment tap)
8. Search google for how to encode your credentials (Client Id and Secret -provided by paypal-) to Base64 (suggested search: base64 encoded credentials pair)
Note- You can use the code in this link here but I don't suggest doing that with your live credentials link : http://tpcg.io/ueL3GObJ
9. In the authorization put "Basic "without the quotes + your Base64 encoded credentials pair