Cannot install apps due to Apple Account not used with App Store error

https://discussions.apple.com/thread/255383137?answerId=260852009022#260852009022

The post at that link implies you can do this without actually adding a payment method.

1. Go into https://music.apple.com (if you can't do it on the app, try doing it in your computer).

2. Sign in and accept Terms and Conditions.

3. Go back to App Store and install whatever you want.

If the above does not work, the resolution to this issue is often making sure you have entered a credit card or other valid method of payment* even if you plan on using account balance to pay for a purchase or the item is free; e.g.: https://support.apple.com/HT204053

- "When you sign in to the App Store and other media services for the first time, you might need to add a credit card or other payment information."

If there is an option to select "Review" or "Continue", select that and enter valid payment information if required. If there's problems doing this:

On a mobile device tap: Settings > [your name at the top] > Media & Purchases > View Account > Manage Payments > Add Payment Method.

Alternatively this document explains how to add a payment method to your Apple Account on an Apple mobile device, a Mac, or a PC; click here --> https://support.apple.com/HT201266

If you continue to have problems contact Official Apple Support - Select your region from the list and then your country from the pop-up window. If you do not see your country, see if there is an "other" listing for that region.

https://getsupport.apple.com/?caller=cups&PGF=PGF63005

*Payment methods that you can use with your Apple ID - https://support.apple.com/HT202631 but note that Apple Account balance may not be eligible to meet what is required in this situation.

Hello~ Do you have a valid payment method in place? See below…

If you can't download or update apps on your iPhone or iPad

~Katana-San~