Unable to get the Relationship option

Hi, I have Meta Box (free version) installed, and have used it to create custom post types and taxonomies. I am trying to use MB Relationship to link the post types that were created using Meta Box. However, the option of Relationship in the menu is not appearing; all I see is Dashboard, Post Type, and Taxonomy. Can MB Relationship not be used with Meta Box – Free version? BTW, I am on WordPress 5.9. Please clarify.