Hello Kas59000,
It sounds as though Screen Time may be blocking use of the app. We'd recommend using these steps to solve the issue: Use parental controls on your child's iPhone, iPad, and iPod touch
Prevent iTunes & App Store purchases
You can also prevent your child from being able to install or delete apps, make in-app purchases, and more. To prevent iTunes & App Store purchases or downloads:
1. Go to Settings and tap Screen Time.
2. Tap Content & Privacy Restrictions. If asked, enter your passcode.
3. Tap iTunes & App Store Purchases.
4. Choose a setting and set to Don't Allow.
You can also change your password settings for additional purchases from the iTunes & App Store or Book Store. Follow steps 1-3, then choose Always Require or Don't Require.
Allow built-in apps and features
You can restrict the use of built-in apps or features. If you turn off an app or feature, the app or feature won't be deleted, it's just temporarily hidden from your Home Screen. For example, if you turn off Mail, the Mail app won't appear on your Home Screen until you turn it back on.
To change your Allowed Apps:
1. Go to Settings and tap Screen Time.
2. Tap Content & Privacy Restrictions.
3. Enter your Screen Time passcode.
4. Tap Allowed Apps.
5. Select the apps that you want to allow.
When you follow these steps, you do not want to block the Facebook Messenger app, but allow access instead. Take these steps to allow your her to download and use the app.
If you're using Ask to Buy or she requests access to this app, then these notifications should show up on your device in Notification Center. Learn more here: Approve what kids buy with Ask to Buy
Lastly, in case this is a school owned device, you may need permission from the school's IT department in order to download additional apps. If that is relevant, then we'd recommend contacting the school's IT department for your next steps.
Let us know if this solves the issue for you or not, take care.
