'Early Adopter' means paying to support a product that doesn't really exist yet in a reasonable state. This was the case when C2 was first proposed many years ago.
New startups generally offer such deals to try and generate money to continue development until a commercial version is realised.
You have to be 'there at the begining' of a new company or piece of software in order to be an Early Adopter.
That option has long since passed for C2.
Hope this makes it a little clearer.