The PayPal payment method works more like cash/check, everything is handled outside of the system.
It’s not a true integration where you can send invoices and receive payment notifications from within Launch27 itself.
Everything will have to be done manually outside of Launch27.
We added it as a payment option for Launch27 users that operate in countries where Stripe credit card payments is not supported. We recommend you not use Paypal if you are able to use Stripe (which all US businesses should be able to).