Group association when user is created?

Hi, thank you for an awesome plugin. I only have one issue in which I hope you can help me with.

When a new user is created, is there a way to automatically assign it’s group depending on which role or ideally which custom meta field that user is associated with.

My client needs to create users which will have different subscription preferences (just 4 custom post types for articles). When the corresponding post type has a new published post the user will get a notification based on their subscription preference.

I have achieved this with your Subscriber Groups and Post Notification section although each user needs to be assigned to the corresponding group manually and hoping there is a way to automate this association or include it as part of the user creation?