How do I download a purchased app on iPad to an iPod touch with a different Apple ID? My daughter purchased an app and put it on her iPad, and I want to put it on an iPod touch that I gave my grandson with my Apple ID. It won't let us do that.
Correct, it won't let you do that.
You'd need to re-purchase it on the other ID, or investigate Family Sharing - one credit card, multiple family members, multiple account IDs, shared apps & content, with Parental Control.