Hi @solutionclick,
This connection guide has more information about how to connect your PayPal account to the PayPal Payments plugin. The official documentation will be extended with more information about it soon.
But when the account has not been connected properly, then the gateway should not be activatable. If you still managed to somehow activate it, the smart buttons likely wouldn’t load and result in this generic error if you click the regular “Place order” button instead. If you require further assistance, you can provide more information in your support thread.
Thanks!
Kind regards,
Niklas