Automatically add job lister to membership level

Hello.

I wan to automatically add a new job lister to a membership level so that the lister can view the job listing exactly as a member would see it.

I believe I would use code similar to this: https://codex.wordpress.org/Plugin_API/Action_Reference/user_register

I’m looking to use the membership level that shows up in the user admin area. So all I want to do is automatically update membership level from “No Memebership” to “Free Membership.”