How to get an old Lego movie off my ipad air?

I have an iPad Air with OS 12.4.6. We have some movies created in the discontinued Lego Movie Maker app.

We can watch the movies in the app, but cannot save them to the camera roll. It says "photo library permission error." But we have checked all the settings a dozen times.

I tried 'screen recording', but the app screen goes black while it is being recorded. Copyright protection I guess.

I tried contacting Lego but they were useless.

I tried gettting at it through ITunes on my PC, but that didn't work.

Is there some fix for this? Can I hack into the files?

I'd try to mirror my screen into another device, if I could figure out how, but then I suspect the app will black that out too.

Please help

Thanks