Is the app for iPads only???

We have a subscription and can access Brain Pop Jr. through our computers and our iPad, but the app will not allow us to log in on our iPhones. We continually get a "login error" message every time. At this point we can only assume it is the app. My kids adore Annie and Moby and all the videos but we all find it very frustrating to not be able to access the entire app on our phones.

Educ8moore about BrainPOP Jr.