Add login authentication to an existing iOS and Android app

I have the xcode project and android studio project already done. The app is complete, i just need the following: - 3 Roles (Admin = me) (Sub admin=People i sell app to) (client= subadmin sees stats of clients) - All 3 can login to the app - Login on both ios and android will show up with email and password with "remember me" checkbox option - Stats will show up for subadmin only for all those under him (his clients) - There is only one main admin (me) - There can be multiple sub admins - Each sub admin will have multiple clients under him - The stats the subadmin sees is # of times the user has logged in - The stats the admin sees is # of times subadmins client has logged in - When opening app immediatly should pop up with login request, if login is not correct then will not be granted access. - Sub admins cannot add clients (only admin can) - Admin (me) can add sub admins and clients under subadmins - We will need a dashboard website where subadmins can login and check stats of there clients, and when Admin logins can see stats of everyone + ability to add new subadmins and clients + ability to delete existing clients and subadmins. You can use existing premade code. I am not picky at all, the login portion i need done within 4 days, the other stuff we can add in after, but i prefer everything be done at once. thanks.