Fitness not available on iPad. It meets all requirements and I have an Apple Watch

So we have 3 iPads in our household. Two 6th gen iPad basic ones and one new mini. My husband and I have Apple watches, I use fitness plus and can’t really see the screen on my phone so I downloaded the app to the iPad. Problem is I can only get it on one of the iPads which is a pain as sometimes my daughter uses it for school or zoom classes. It would be much easier to have the app available on all the iPads and just use whichever one is free. I can’t for the life of me figure out why the app isn’t available on the other two iPads. It’s also frustrating I can’t use my MacBook! Who on earth can follow those exercise classes on a tiny phone screen?