Two things are the same whichever API you integrate: you need an OAuth 2.0 client of your own, and you can do most of the plumbing against a stub before anyone at Cleverbase has to register anything for you.
A client is registered by hand, together with your account manager, because the redirection URIs and the display name end up in front of real users. The stubs need no registration at all: every service publishes one, and they all accept the same development credentials.