That's great, thanks for letting us know about the issue. Regarding Cardinal - you can sign up for the credentials through the link in your Settings > Payment Provider > Manage. There is a link to an FAQ and at the bottom of the page you can sign up for the credentials. There is a specific form there for PayPal. It might take a few days for Cardinal to issue those but if you haven't heard from them since April I would advise checking in or trying again.
Let me know if you have any problems.
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Merchants using Shopify Payments, Stripe, or PayPal Express are automatically compliant with PSD2. Merchants using a third party gateway may be asked to sign up for Cardinal Commerce, a third party 3D Secure provider. You can add your Cardinal credentials in the Shopify Admin under Settings > Payment Provider > Manage. If you do not have credentials yet, you can fill out the application form that is also linked in the same admin section. Merchants using PayPal Payflow Pro may not see an option to add their Cardinal credentials. In this case you should disable PayPal Payflow Pro and enable PayPal Website Payments Pro (UK) using the same Payflow Pro credentials. You will then see the Cardinal option. If there is no option to integrate with Cardinal, then reach out to your payment gateway and ask if they are PSD2 compliant and working with Shopify. If not, then we recommend choosing an alternative gateway that is compliant.
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