If your coloring pages aren't appearing, try restoring your purchases. To do this, follow the steps below:
Tap on either the "Disney & Pixar Coloring Books" or the "Marvel Coloring Books"
Tap "I need to print pages"
Tap the "Restore Purchases" button at the bottom of the screen
If your pages are still not available, ensure you're signed into your device with the Apple ID or Google account that made the purchase.
Open "Settings", then tap on "iCloud". If the Apple ID in the iCloud section is not the one that made purchases in Disney Color and Play AR, sign out and login with the correct ID.
Open the "Play Store", and tap the "Settings" icon (3 horizontal bars) in the upper left. Tap on "Account". If you have multiple accounts listed, select the one that made purchases on Disney Color and Play AR.