Kids+ missing from the Kindle app on iPad

If this is the wrong forum, please delete/advise. I could not find a Kids + forum.

I have downloaded the Kindle app onto my grandchildren's iPads. Both have been added to my Amazon account profile with the Kids + Unlimited attached to their profile. However, on the actual Kindle app, designated under their profile, the Kids + is not showing. Only my book collection is showing. I need quick help as they leave to go overseas x 3 years. This will be their only access to books in English. (Note: I have downloaded the Parents Dashboard with both kids profile showing. I've also selected books to get started but none on showing on the Kindle app (despite syncing). I'm sure I'm missing a step...