1) Open the Apple App Store, go to your account page

2) In the center of the page, click Redeem, Gift Card Or Code

3) Enter your code manually

4) Enter the promo code and tap on "Redeem"

5) Click "Done”
More Information

No. Apple's built-in privacy safeguards mean’s your screen time data, apps, categories and websites you block are confidential and inaccessible to Offline

Sometimes Apple Screen Time Data takes awhile to load, hit the refresh data button at the top right of the homepage

The reason the data looks different from Apple Screen Time data is because Offline only gets to display the data from the time you give permission.

Any previous data before that time isn't available to be displayed