You will have the option to pay with a credit card or NRVE. Narrative uses Paypal; therefore, you can pay with Paypal, credit card, or Venmo (if on mobile in the US) in the countries that PayPal supports.
If you pay by NRVE, you will need to transfer from a NEP-5 Token Wallet. You can not transfer your Narrative Rewards points directly from the platform to pay. You can redeem your NRVE points into a wallet and then pay.
Here is an FAQ for setting up a Wallet.
Here is the FAQ for Redeeming NRVE points you earned in Narrative.