Membership plugin setup with PayPal Express fails to charge.

I've setup my Membership plugin and have been trying to successfully subscribe to a Paid account that costs €0.01, but PayPal fails to charge.

I am able to Register and a WordPress user gets created. Next, I select a subscription and it sends me to PayPal website where I login with my personal PayPal account. I am successfully logged in and am presented with a 'Review Your Payment' screen showing my payment method and conversion from euro to 0.02 USD, everything seems correct. I click 'Agree and Pay' and get this error (everytime):

The PayPal site is currently experiencing technical difficulties with our credit card processor. We are working to solve this problem as quickly as possible. If you would like to Send Money, please fund your payment with your PayPal balance, PayPal Credit or bank account. If you would like to use your credit card, please return to the PayPal website later to complete your transaction. We apologize for any inconvenience this may cause.

What could be the problem? I've checked all the configuration settings for Membership, and nothing seems to be missing.