Organizations are another type profiles, like Persons, so they can't be create like other content, it has to be created as profile. If you need organizations as content module it maybe it make sense to use Groups module for this, by the way it's possible rename Groups to Orgs in Studio > Polyglot > Keys. 

In upcoming version we'll add an option to redirect to add Person (or Organization)  after join, without asking which type of profile user want to create