You may be a few users who can not download new Apps because you're having trouble using the App Store. If so try with the solution that we offer below. Sometimes, if the time or date of your iPhone, iPod touch or iPad is not properly configured, the App Store does not allow download new applications. It is a problem that does not always happen but it can happen in some devices.
The way to fix it is very simple. All you have to do is go to Settings> General> Date and time> Automatic adjustment.
After a few minutes, the time of your iPhone should automatically adjust to the current. If you do not, you can change it manually. After getting a correct time and date, possibly the App Store will run smoothly again.
Another option
If the problem persists, it could be as simple fix. Many times when we changed version of iOS, Apple introduced changes in its policy that if we do not accept, they prevent us from using the service. To correct this error, let Settings> iTunes Store and App Store and enter the data from our Apple account again. After the authentication, surely we will be asked to accept the terms and conditions of the App Store again (here's the problem that prevents us from using the store) and problem solved.
Could Apple, not our iPhone
After testing the options previously mentioned, if we continue to present problems for the connection, the problem may be Apple, and not us. We can try it by doing a simple Google search on whether there are any problems with iTunes and iCloud servers.