My Samsung pay wouldn't setup. Decided to delete the app and reinstall it. Over WiFi it setup with no issues at all Mine is on the Z Fold 3 I'm on 3UK as well. I will say I haven't used the card from the phone yet
I believe that there is a fix on the way with a software update. As a few have had issues. Worth contacting Samsung support as well. I take it yours is a UK version phone. Non UK phones won't work as I found out a while ago
It is indeed UK phone as i placed order in Samsung Online shop UK. Anyways i also ordered for a replacement sim card and will see if it can help me in carrier settings upgrade. If not i will have to wait for Samsung to push the update for fixing this. But i do fear that there are few other model devices there which has the same problem and Samsung did nothing so far.
Finally this got resolved. Not sure if the settings came on its own or is it because i raised a complaint with Samsung Technical Team who took IMEI and order number and told they would update it from backend within 48Hrs. Doesn't matter now as it is finally solved.