App no longer supported

Hi I've recently got a new iphone, I hadn't noticed that an app "My Media" had stopped being able to update with the release of a new iOS, I'm thinking maybe since 14 or 15 it's stopped updating. I've set up my new phone but can't download the app on my new phone. The app won't open on my old phone either but still has an icon, I haven't yet cleared/ reset the old phone in case there is a way of accessing the photos I had saved within the app. Does anyone know of anything I can use? I'm getting to the point where I'll need to blank it to give to my daughter. (If it makes any difference the old phone is an iphone 11 and I think it's running ios15 now.)

Thanks