Why cannot I download any app?

According to: If you see a message that says 'Your account has been disabled in the App Store and iTunes' - Apple Support

"Contact Apple Support for help.

If you see a message that says "Your account has been disabled in the App Store and iTunes," there might be a problem with the payment method that you have on file.

When you see the message, don't try to edit any of your account information. Instead, contact Apple Support for help."

Might your iPhone be restricted?

Check Settings > Screen Time

amrita84 wrote:

It says disabled

What might "it" mean exactly?

What other words appear besides "disabled"?