You can checkout using Credit card (via Stripe) also.
Once you are logged into the site, simply go to the page of the addon then click on the “Add to Cart” button:
It will take you to the checkout page where you can see the shopping cart. Click on the payment method dropdown and select “Credit Card” then hit the checkout button.
I just did a test using PayPal and it takes me to the paypal checkout page correctly. So not sure why your browser isn’t going to PayPal.