My child's school forces us to create accounts the way you describe. Since kids all get ipads they need icloud accounts, but the school does not participate in the program that lets them create icloud accounts for kids. You as a parent must create the account. If you don't use apple products, I don't, you can only create an adult account. You cannot create a child account, or manage it once created, without another apple device. I went through all the steps to create an adult account, then logged out of the ipad and used the child account I created, but the account was useless without me being logged into the parent account on an apple device. You could not use the web-ui from a linux or windows device. I complained to the school and said I thought this was a violation of the laws for children under 13. They said the child doesn't own the account, I do as the parent and give them permission; so it's fine. There was no other choice to setup the devices for my children.