App Store problem

What happens when you try? Error message(s)? More information would help. Account disabled?

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

Contact iTunes Support. See the Apple Support articles below for contact information.   

iTunes Support – world wide 

Apple Support schedule phone call       

Do you have access to another WiFi network where you can try? That has worked for several people.

Try a restart.

Restart your iPhone, iPad, or iPod touch         

Try a forced restart.

Reset Device.      

If necessary

Hard reset.        

Do a backup and try a factory reset. Then restore from your backup.

Restore to Factory setting.      

Backup - Restore your device from an iCloud or iTunes backup.      

"Other apple device" includes your iPad Air.

My post covers you iPad Air.

See If you can’t download or update apps on your iPhone or other Apple device

https://support.apple.com/en-us/HT207165

After reading the document, use this link from it if you need to contact Apple Support.