Hi,
I've made two tests on your website:
- The first time, I used a fake address and kept the default country "Saint Martin" and I got the issue you described. If I check the console of my browser at that time, it says this:
i.imgur.com/ZIYJR78.png
As you can see, it doesn't like the country code.
Here is a list of all the accepted country codes:
developer.paypal.com/api/rest/reference/country-codes/
So you need to make sure the country zones you're using are available in that list or the payment will be refused by PayPal.
- The second time, I tried with an address in the USA, and the popup worked just fine. So it confirms that the problem is with the country code.