Thank you for sharing these details.
For what you're trying to achieve, the standard WordPress user roles and the Toolset's Access features won't work.
You'll need an approach where you'll be managing a parallel system of user roles and relationships:
1. All users will register on the website with a standard user role.
2. You'll add a new custom post type 'User Profiles' on the website. After registering, each user will create a new post in this post type as an author, which will serve as his/her profile post. This anchoring is needed because a relationship can be created between two post types, but not between users and the post types, directly.
3. Next, the main 'Listings' post type and the 'User Profiles' post type will need to be joined together, through a many-to-many relationship.
( ref: https://toolset.com/course-lesson/many-to-many-post-relationships/ )
This means that when a user will visit a certain listing posts page, a relationship form will be there which can be used to connect his/her 'User Profile' post with the current 'Listings' post. This connection will serve a kind of a sign up by the user for this particular listing.
4. For controlling the role of the sign up, you can include a 'Role' custom field with the intermediary post while creating a many-to-many relationship.
This way, the user will be able to select which role or capacity the user is willing to sign up or link with the current listing, while using the relationship form.
5. With the above things in place, rest of it would involve using the conditions to check whether the current user is linked to the current listing post or not and in which role, to determine what other activities can be performed by him/her with that particular listings.
I hope this makes sense and let me know if you have any follow up questions