Unable to download apps from App Store

This Apple Account has not yet been used with the iTunes/App Store -

On a Mac;

• Open the System Settings app (in the  menu)

• Choose your Apple Account

• Choose Media & Purchases

• Choose View Account

• Choose Manage Payments

• Add a payment method to your account details

On an iOS/iPadOS device;

• Open the Settings app

• Choose your Apple Account

• Choose Media & Purchases

• Choose View Account

• Choose Manage Payments

• Add a payment method to your account details

You can find the acceptable payment methods for your country here;

https://support.apple.com/es/HT202631

M1 Mac mini, macOS 15.5;  Watch, series 10 GPS-only, watchOS 11.5; iPhone 16, iOS 18.5; TV 4th Gen, tvOS 18.5 HomePods, audioOS 18.5

seren128 (Author)

Perhaps to set up an initial Apple account in iTunes (for PC?) could

be an answer. Depends on what other device or computer you have.

Sign in and manage your Apple Account on iPhone - Apple Support

//support.apple.com/guide/iphone/sign-in-and-manage-your-apple-account../ios

Sign in to your Apple Account

If you didn’t sign in during setup, do the following:

1. Go to Settings .
2. Tap Apple Account.
3. Tap one of the following:

• • Use Another Apple Device: Bring your other iPhone or iPad (with iOS 17, iPadOS 17, or later) nearby, then follow the onscreen instructions.
  • Sign in Manually: Enter your email address or phone number, then enter your password. If you don’t have an Apple Account, you can create one.

1. If you protect your account with two-factor authentication, enter the six-digit verification code.

If you forgot your Apple Account password, see the Reset your password website.

***

PS: edited to add..

Sign in to your Apple Account on the web or in your device settings - Apple Support

Also see:

Apple Support article: Manage and use your Apple Account

Keep your Apple Account secure on iPhone

Apple Account website

[There may also be other details on how to resolve your issue.]