There are 3 reasons why the registration of your card failed.
You are using a debit card. UBS TWINT supports a direct account connection as a payment method. To do this, select a UBS account instead of a debit card. Alternatively, you can also register a credit or prepaid card as a payment method.
You are using a corporate credit card. The UBS TWINT guidelines do not allow the usage of corporate credit cards. In UBS TWINT only a credit card, prepaid card or a UBS account is permitted as a payment method.