@TeeKay, Cardinal Cruise doesn't work with Shopify. The default credentials that Cardinal supply are for Cruise but the fields in the Shopify setup don't use those values. You have to request the 3D Secure Credentials for your Paypal Pro account instead.
To be honest I've missed the most recent discussions in this thread as I stopped following once I had it running but I was contacted by PayPal over a year ago and they created a Cardinal account for me. I didn't bother implementing it as I had been running on PayPal Pro US for years as Shopify didn't properly support the UK version. At the beginning of October transactions that weren't going through PSD2 checks on PP US started to fail so I switched to UK then as they had obviously fixed it in the meantime. That's when I realised the Cruise configuration wouldn't work so I got them to send me the 3D Secure config instead which has worked fine ever since with thousands of transactions going through on Visa and Mastercard in my Cardinal dashboard.
Maybe it's not compatible with the newest standard that is supposedly being implemented (believe it when I see it seeing as how many delays there were getting to this stage) but Cardinal have said nothing to me and I've had regular contact with them over the last two months.
I'm in the same position as yourself i.e. I have the 3D Secure Credentials from Cardinal for Website Payments Pro (UK). Not currently using them mind.
But yes, it seems we are in a sticky situation come January 1st as regards customers form EU countries wanting to pay by card and their banks requesting PSD2 level of authentication (which as I understand isn't an immediate issue for yourself with only selling to the UK and that not being mandatory until September 2021).
Hopefully Cardinal get their Cruise PSD2 service sorted out between PayPal UK and Shopify soon.
Or alternatively (and as I begin to sound like a broken record) — Shopify! please work with PayPal to allow their Smart Payment Buttons to work within the Shopify checkout flow, and I'll happily forget about this Cardinal Cruise integration altogether.
Has anyone resolved the issue of PayPal Pro PSD2 as discussed in this thread. We just learnt last week that Cardinal Commerce is unable to help us but we are getting nowhere with PayPal. I have emailed firstname.lastname@example.org but am still waiting for a response.
Not going to happen I guess. Last contact with Shopify just resulted in a "switch to Shopify payments" pitch. I think Shopify see this as a gift to get those who can switch to do exactly that. For those who can't, too bad. Won't affect my remaining Shopify site until it gets introduced into UK and I will be gone from here by then. 3DS working fine on my Woo Commerce site.