That can happen when you are trying to use a live card in test mode.
You must use test cards in the test mode to test the payment and the flow. Once you are done with the testing then you can make it live by disabling the setting from Invoicing->Settings->Payment Gateways->Stripe->Enable Test Mode.
Make sure you fill in all the card details. Failing to provide CVV will also cause an error.
To open a new support ticket, first select the relevant forum and then click the "New Post" button. Example: You need support for the core plugin? Click on Core Plugin support and click on the "New Post" Button.