Hello and welcome to Apple Support Communities, Edward!
I understand you're trying to download an app from the App Store and are able to enter the password correctly, but when prompted to enter the authentication codes, you do not have a space to enter them. I'd be happy to provide you with information to help you resolve this.
Check out the steps in this article: Two-factor authentication for Apple ID
"What if I use two-factor authentication on a device running older software?
If you use two-factor authentication with devices running older OS versions—like an Apple TV (2nd or 3rd generation)—you might be asked to add your six-digit verification code to the end of your password when signing in. Get your verification code from a trusted device running iOS 9 and later or OS X El Capitan and later, or have it sent to your trusted phone number. Then type your password followed by the six-digit verification code directly into the password field."
Thank you for using Apple Support Communities.
Have a great day!