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.      

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.

My post covers you iPad Air.

"Other apple device" includes your iPad Air.