When your physical card arrives, you need to activate it before you can use it:
Log in to app.neno.co
Go to Cards in the left sidebar
Select the card you want to activate
Navigate to Physical Card and follow the activation steps
Your first transaction with the physical card must be a chip-and-PIN transaction (not contactless) to complete the activation process. After that first chip-and-PIN transaction, you can use contactless payments normally.