Ah, the classic "Apple ID has not yet been used in iTunes" loop, huh? It can be a frustrating one, that's for sure.
Let's break it down:
1. **Different Accounts**: First off, just so we're clear, Google account and Apple ID are two separate entities. Signing into Google won't do anything for your iTunes situation, so make sure you're using your Apple ID for iTunes.
2. **Review Process**: The message typically means that Apple wants you to agree to new terms and conditions or finish setting up your Apple ID. Sometimes this involves payment information, even for free apps.
Here's how you can try to resolve this:
### Option 1: Via Settings
1. Go to the iPad Settings app.
2. Scroll down to your Apple ID (usually your name at the very top) and tap on it.
3. Go to "Media & Purchases" and tap on your ID.
4. Select "View Account," you may need to enter your password again.
5. Look for an option to review your account information. Make any necessary updates. You may have to add payment info, even if the app is free.
### Option 2: Via App Store
1. Open App Store and click on your account icon at the top right.
2. Choose your Apple ID, then choose 'View Apple ID'.
3. You might be asked to authenticate; go ahead and do that.
4. Scroll down to see if there's an option to review/update your account information.
### Option 3: Via iTunes on a Computer
If the above doesn't work, some people have had luck doing this via iTunes on a computer.
1. Open iTunes.
2. Sign in with your Apple ID.
3. Go to "Account" then "View My Account".
4. Look for the 'Review' options.
### Option 4: Contact Apple Support
Sometimes, nothing works and you gotta bring in the big guns. Apple Support can usually sort this out pretty quick.
If all else fails, you might have to reset all settings on your iPad (last resort, obviously).
Remember, even after fixing the issue, you'll probably have to sign out and sign back in to the App Store or iTunes.
Hope this helps, mate! Let me know how it goes.