Hi there.
I never even considered that when I bought my iPad b/c I didn't know about the adobe bit. However, I don't seem to have any problem downloading anything from ancestry. I have an iPad3 and have NOT downloaded the ancestry app. I simply type ancestry.whatever into the search engine, log in, and away I go, just like on my laptop. So maybe the app is the problem? It seems to me that it has some limitations which was why I didn't download it, if I remember correctly.
PB