different registrations forms

CB Conditional just shows/hides tabs/fields based off conditions. It doesn't assign anything.

To assign a usergroup based off a field value you will need CB Auto Actions for that. You seam to be confusing CB GroupJive groups with Joomla usergroups though? Are you needing to assign a Joomla usergroup or force them to join a CB GroupJive group based off the field value? Below is the initial CB Auto Actions setup you'll need, but the action setup will vary a little depending on which of those you need.

Global
Triggers: onAfterUserRegistration, onAfterNewUser, onAfterUserUpdate, onAfterUpdateUser
User: Automatic
Access: Everybody
Conditions
Field: cb_registrierung_als
Operator: Equal To
Value: Händler

This would act on frontend and backend registration and profile edit. It will check if the field cb_registrierung_als as a value of Händler. If it does then whatever action type you selected will execute.

Hi Kyle, thanks for the quick reply and your input!

I need to assign a Joomla usergroup at the registration, depending of if the user is retailer, consumer or producer.

Best regards Uwe

Wow, I´ve got it! Very great! Thanks a lot, Kyle!

Hi Kyle, my last question in this "case": you mentioned, the necessary triggers are: onAfterUserRegistration, onAfterNewUser, onAfterUserUpdate, onAfterUpdateUser-
I only need this autoaction in the registration-process. Do I need all the 4 triggers anyway?
Best regards Uwe

I only need this autoaction in the registration-process. Do I need all the 4 triggers anyway?

Those triggers are as follows.

Backend
Registration = onAfterNewUser
Edit = onAfterUpdateUser

Frontend
Registration = onAfterUserRegistration
Edit = onAfterUserUpdate