Hi Mike a little late in response to this question, but I was just researching the same issue above. It appears that only the administrator log in works when signing in, the rest of the users in the group are unable to access the web application using their credentials. Is there something in the role I might need to adjust? Any suggestions? Thanks!
Kara,
There is nothing in the roles you need to adjust. Roles don't control access to items.
If you want people in a group to be able to see your web application, you need to make sure the web application and the items the web application references are also shared to the group. This includes the web map and any hosted layers the web map might include.
Thanks,
Mike