As a first step, you should perform a forced-restart of your iPad - as doing so will often resolve an isolated software issue:
- On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
- On other iPad models: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.
If the issue remains unresolved:
If you can’t download or update apps on your iPhone or iPad – Apple Support
You should also check your ScreenTime restrictions:
- Settings > Screen Time > Content & Privacy Restrictions > iTunes & App Store Purchases > Adding Apps - ensure that this permission is set to Allow
- Settings > Screen Time > Content & Privacy Restrictions > iTunes & App Store Purchases > Deleting Apps - ensure that this permission is set to Allow
If still unresolved, you might be best advised to seek assistance directly from from Apple Support. You can contact the Support Team using the Get Support link at top-right of this page. Alternatively, you can initiate and manage your support cases using the excellent Apple Support App. If not already installed on your iPad - and in recognising that you are having difficulties with installation of Apps on your iPad - the App can be downloaded from the App Store:
https://apps.apple.com/gb/app/apple-support/id1130498044
Should you have access to another Apple device, such as an iPhone, the Support App can be installed and your case managed from there.