Beyond the installation documentation and the help videos (see above post by jojo12) there is no further information, sorry.
Incuabtor projects come with no documentation however CB Invites is pretty straight forward; install it, enabled it, view your profile, invite someone by email address, done.
Fatal Error sometimes is not helpful. Again, please upgrade to GJ 2.5.1 if not done so already. Check GJ > Integrations to ensure the integrations are also 2.5.1. You likely have some sort of conflict present however.