Every thing appears to be set up correctly, the plugin is showing up on my order form but every time I try to test it I get this screen:
Ok first of all 
welcome to the community,
I went ahead and split your post into a new topic, so we can track it freely.
If you get any issue on the Paypal side there are few reasons that could be happening:
1. Forgot to setup your Paypal account:
On our app each funnel can have a different Paypal account (recipient account), please check under your Funnel > Optional > Paypal ID. (Also make sure to setup a default paypal on your account level).
2. You didn’t setup a currency (very unlikely):
The same way a Paypal Email/ID is set.
3. Have a wrong amount to be charged:
For some europeans, they try to input their product prices with a comma “,” instead of a dot “.” which doesn’t work for paypal…
Hope that solves your issue, let me know if you have more questions
Best,
– @yassine