In order to use the CB Auto Assign ACL Group plugin you must take 2 steps before you configure the plugin;
Create all the acl groups for your Joomla site as normal by going to User Management >> Groups
Create at least one CB field that will be used to control the ACL group of the CB users. For the purposes of this tutorial we will illustrate only 1 single select cb field however you can set up as many CB Fields of any type to control ACL with this plugin.
Ensure that the values of each option are EXACTLY THE SAME as the user groups you created in step 1. for example if you want your users to be in the Registered user group create an option called Registered for the CB Field then all users who choose that option will be added to the Registered group.
Note that you can use any CB Field type and any user group including custom user groups that you create yourself.
The CB Field(s) that you created in step 2 that hold the ACL groups must be specified in the last plugin parameter. Ensure the plugin is enabled