SIM card not valid

Bought a Uno mobile data card and installed it in an unlocked iPhone X Max (bought in Apple store) to travel to Italy - installed SIM card which has been activated according to Cellular abroad but get message that the card is not valid, is from a service provider that is not supported under the activation policy currently assigned by the activation server...

Any thoughts or help from anyone or has anyone has experience with cards from this provider (Cellular abroad is the US representative for Uno mobile)