I'm having trouble installing Cashapp in a new iPhone

If you encounter any challenges with third-party applications, the best course of action is to directly contact the app developer for further assistance. Here's a brief guide on how to do it:

1. Identify the app developer.
2. Visit their website or app store listing.
3. Look for their contact information or support channels.
4. Clearly describe the issue you are facing.
5. Provide any necessary information they may need.
6. Follow their instructions and provide feedback.
7. Be patient and follow up if needed.

By reaching out to the app developer, you increase your chances of receiving accurate and personalized support for the challenges you're experiencing. To contact an App developer --> How to contact an app developer - Apple Support

If one or more of the following 6 options are true then you can't choose None as a payment method then the Billing information is needed. The "None" option will not appear...

1. If you have an unpaid balance or payment due
2. If you have a subscription that automatically renews
3. If you're using the iTunes Store or App Store for the first time
4. If you are not in the country or region you’re creating an Apple ID for
5. If you changed your country or region
6. If you're a part of Family Sharing

If you can't download, make purchases, or update apps, including free apps, you must update your payment method or add a new one. If you verified that a payment method is available in your country or region and you're still having trouble, learn more.

For getting access code through SMS you need to have an SMS/MMS plan enabled by your carrier for the SIM/eSIM that you use on your device. Apple Inc does not provide SMS/MMS services.