I understand you are having an issue with making a purchase from the App Store from your iPhone. I have an article that could address the issues you might be facing.
First, start with this article to address issues connecting to the store,
If you are having other issues with the App Store, please explain exactly what happens when you try to make a purchase, including any error message that you may be getting.
This thread has been closed by the system or the community team.
You may vote for any posts you find helpful, or search the Community for additional answers.
Why I can't purchase app store
Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple Account.