You can set up an authenticator app to send a notification to your mobile device or to send you a verification code as your security verification method. You aren't required to use the Microsoft Authenticator app, and you can select a different app during the set up process.

How to redeem a code on Xbox Series X|S and Xbox One. Press the Xbox button to open the guide, and then select Store. Press the View button to open the side menu, and then select Redeem. Enter the 25-character code, select Next, and then follow the prompts.