Unable to download applications on iPhone 6

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

If you can't choose None as a payment method only if...

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

What issues are you seeing?

Please see this https://discussions.apple.com/thread/254585728?answerId=258806716022#258806716022

for iOS12.5.7

No too long ago YouTube was installed on 12.5.5 iPhone.

Instagram is not an Apple Product. Contact the app developer here --> App Support  or Instagram Help Center

Facebook is not an Apple product. Contact the app developer here --> App Support or Facebook Help Center | Facebook

YouTube is not an Apple Product. Contact the app developer here --> App Support or YouTube Help - Google Support