I would like to make it so that when their group id is entered by the web application or some other info is entered that they will be promoted to member rank on the mc server. what do I have to set to make this happen?

I guess what I am asking is if I set the registered and unregistered groups what determines if the player is registered with the web application?

also can that determination factor be changed to something else?

CommunityBridge assumes if a player has a userID they are registered. How it is determined depends somewhat on your particular configuration. There's three basic approaches to matching a Minecraft Player to a web application user ID:

a) The player's web application username is the same as their player name (lookup by username). No longer recommended configuration due to the coming UUID/player name changeability.
b) A custom profie field for the player's Minecraft player name. No longer recommended configuration due to the coming UUID/player name changeability.
c) A custom profile field for the player's UUID string. This is now the safest choice given the coming feature of being able to change your player name.