A recent Apple update changed the pop-up option from Allow Pop-ups to Block Pop-ups.
Looking at the screenshot below, when you glance at pop-ups and see that it's green, it can be confusing.
To rectify this, please follow these steps;
Tap Settings on your iPad/iPhone
Under General, toggle Block Pop-ups to off, it will go grey
Go back to Kinderly and click on the paper icon
You will see the following message, tap Allow