Welcome to iPad Forums!
A few things to try:
Check your Wi-Fi connection: try streaming a video to see whether or not it loads quickly.
Connect to a different Wi-Fi, and see if that solves the problem.
Restart your device - just turn it off and on again.
If you still have problems downloading apps, go to the Settings app, select your name - iTunes & App Store, tap your Apple ID and sign out. Then restart your iPad, and sign in again.
In Settings - General - Date & Time, make sure you’ve got the right time zone. If “Set Automatically” is enabled, turn it off, then restart your iDevice, and turn this feature on again.
In Settings - Wi-Fi, disconnect by selecting “Forget this Network”. Then set up your Wi-Fi again.
One more option would be to reset all settings in Settings - General - Reset. This will set back everything to default, but you won’t lose any data. You’ll have to see through the Settings app afterwards, and select what you prefer.
If you also get a message about billing or payment, take a look at Apple’s instructions:
If your payment method is declined in the App Store or iTunes Store
Hope that helps.