Have you enabled an age-rating restriction? Basically all browsers are 17+, except ones specifically curated for kids. This could also explain why it looks like it installs, then disappears, because it would actually allow install and then blacklist the app, so it's on there...just unusable

Also, why would you want to enable a web proxy on a supervised device? I'm not sure that, in the situations I'm aware of, limited Flash compatibility outweighs totally bypassing an institutional firewall (and in the case of a school, possibly violating CIPA)

Puffin is rate 17+. When age restrictions are enforced in a configuration the app will install and disappear. For us Puffin was really only needed when we utilized an online resource that leverage Flash, that being CompassLearning. I see it having a brief tenure with our school.

Try Puffin Academy instead. It's a curated list of sites rather than a full blown browser:

https://itunes.apple.com/us/app/puffin-academy/id716707933?mt=8

You guys are awesome. I tried Puffin Academy and it works with our Spanish textbook website. Thank you so much.